Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (
North American
North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Ca ...
cereal grain
A cereal is any grass cultivated for the edible components of its grain (botanically, a type of fruit called a caryopsis), composed of the endosperm, germ, and bran. Cereal grain crops are grown in greater quantities and provide more food ...
first domesticated by
indigenous peoples
Indigenous peoples are culturally distinct ethnic groups whose members are directly descended from the earliest known inhabitants of a particular geographic region and, to some extent, maintain the language and culture of those original people ...
in southern Mexico about 10,000 years ago. The leafy stalk of the plant produces pollen
inflorescence
An inflorescence is a group or cluster of flowers arranged on a Plant stem, stem that is composed of a main branch or a complicated arrangement of branches. Morphology (biology), Morphologically, it is the modified part of the shoot of sperma ...
s (or "tassels") and separate ovuliferous inflorescences called
ears
An ear is the organ that enables hearing and, in mammals, body balance using the vestibular system. In mammals, the ear is usually described as having three parts—the outer ear, the middle ear and the inner ear. The outer ear consists o ...
that when fertilized yield
kernels
Kernel may refer to:
Computing
* Kernel (operating system), the central component of most operating systems
* Kernel (image processing), a matrix used for image convolution
* Compute kernel, in GPGPU programming
* Kernel method, in machine learnin ...
or seeds, which are
fruit
In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering.
Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in particu ...
s. The term ''maize'' is preferred in formal, scientific, and international usage as a common name because it refers specifically to this one grain, unlike ''corn'', which has a complex variety of meanings that vary by context and geographic region.
Maize has become a staple food in many parts of the world, with the total production of maize surpassing that of
wheat
Wheat is a grass widely cultivated for its seed, a cereal grain that is a worldwide staple food. The many species of wheat together make up the genus ''Triticum'' ; the most widely grown is common wheat (''T. aestivum''). The archaeologi ...
or
rice
Rice is the seed of the grass species '' Oryza sativa'' (Asian rice) or less commonly ''Oryza glaberrima'' (African rice). The name wild rice is usually used for species of the genera '' Zizania'' and '' Porteresia'', both wild and domesticat ...
. In addition to being consumed directly by humans (often in the form of
masa
''Masa'' (or ''masa de maíz'') (; ) is a maize dough that comes from ground nixtamalized corn. It is used for making corn tortillas, '' gorditas'', ''tamales'', '' pupusas'', and many other Latin American dishes. It is dried and powdered into ...
flour corn
Flour corn (''Zea mays'' var. ''amylacea'') is a variety of corn with a soft starchy endosperm and a thin pericarp. It is primarily used to make corn flour.
This type, frequently found in Aztec and Inca graves, is widely grown in the drier parts ...
, and sweet corn. Sugar-rich varieties called sweet corn are usually grown for human consumption as kernels, while
field corn Field corn, also known as cow corn, is a North American term for maize (''Zea mays'') grown for livestock fodder (silage), ethanol, cereal, and processed food products. The principal field corn varieties are dent corn, flint corn, flour corn (also ...
varieties are used for animal feed, various corn-based human food uses (including grinding into cornmeal or
masa
''Masa'' (or ''masa de maíz'') (; ) is a maize dough that comes from ground nixtamalized corn. It is used for making corn tortillas, '' gorditas'', ''tamales'', '' pupusas'', and many other Latin American dishes. It is dried and powdered into ...
, pressing into corn oil, fermentation and distillation into alcoholic beverages like bourbon whiskey), and as feedstocks for the chemical industry. Maize is also used in making
ethanol
Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a ...
and other biofuels.
Maize is widely cultivated throughout the world, and a greater weight of maize is produced each year than any other grain. In 2021, total world production was 1.2 billion
tonne
The tonne ( or ; symbol: t) is a unit of mass equal to 1000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton ( United State ...
s. Maize is the most widely grown grain
crop
A crop is a plant that can be grown and harvested extensively for profit or subsistence. When the plants of the same kind are cultivated at one place on a large scale, it is called a crop. Most crops are cultivated in agriculture or hydropon ...
throughout the Americas, with 384 million metric tons grown in the United States alone in 2021.
Genetically modified maize
Genetically modified maize ( corn) is a genetically modified crop. Specific maize strains have been genetically engineered to express agriculturally-desirable traits, including resistance to pests and to herbicides. Maize strains with both tra ...
cultigen
A cultigen () or cultivated plant is a plant that has been deliberately altered or selected by humans; it is the result of artificial selection. These plants, for the most part, have commercial value in horticulture, agriculture or forestry. Beca ...
; human intervention is required for it to propagate. Whether or not the kernels fall off the cob on their own is a key piece of evidence used in archaeology to distinguish domesticated maize from its naturally-propagating teosinte ancestor. Genetic evidence can also be used to determine when various lineages split.
Most historians believe maize was domesticated in the
Tehuacán Valley "By faith and hope"
,
, image_map =
, mapsize = 300 px
, map_caption = Location of Tehuacán within the state of Puebla.
, image_map1 = Puebla en México.svg
, mapsize1 = 300 px
, ma ...
of Mexico. Recent research in the early 21st century has modified this view somewhat; scholars now indicate the adjacent
Balsas River
The Balsas River (Spanish Río Balsas, also locally known as the Mezcala River, or Atoyac River) is a major river of south-central Mexico.
The basin flows through the states of Guerrero, México, Morelos, and Puebla. Downstream of Ciudad Alta ...
Valley of south-central Mexico as the center of domestication.
An 2002 study by Matsuoka ''et al.''. has demonstrated that, rather than the multiple independent domestications model, all maize arose from a single domestication in southern Mexico about 9,000 years ago. The study also demonstrated that the oldest surviving maize types are those of the Mexican highlands. Later, maize spread from this region over the Americas along two major paths. This is consistent with a model based on the archaeological record suggesting that maize diversified in the highlands of Mexico before spreading to the lowlands.
Archaeologist Dolores Piperno has said:
Since then, even earlier dates have been published.
According to a genetic study by the
Brazilian Agricultural Research Corporation
The Brazilian Agricultural Research Corporation (Embrapa - pt, Empresa Brasileira de Pesquisa Agropecuária) is a state-owned research corporation affiliated with the Brazilian Ministry of Agriculture. Since its inception on April 26, 1973, it ha ...
(Embrapa), corn cultivation was introduced in South America from Mexico, in two great waves: the first, more than 6000 years ago, spread through the
Andes
The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long, wide (widest between 18°S – 20°S ...
. Evidence of cultivation in Peru has been found dating to about 6700 years ago. The second wave, about 2000 years ago, through the lowlands of South America.
The earliest maize plants grew only small, corn ears, and only one per plant. In Jackson Spielvogel's view, many centuries of artificial selection (rather than the current view that maize was exploited by interplanting with '' teosinte'') by the indigenous people of the Americas resulted in the development of maize plants capable of growing several ears per plant, which were usually several centimetres/inches long each. The
Olmec
The Olmecs () were the earliest known major Mesoamerican civilization. Following a progressive development in Soconusco, they occupied the tropical lowlands of the modern-day Mexican states of Veracruz and Tabasco. It has been speculated that ...
and
Maya
Maya may refer to:
Civilizations
* Maya peoples, of southern Mexico and northern Central America
** Maya civilization, the historical civilization of the Maya peoples
** Maya language, the languages of the Maya peoples
* Maya (Ethiopia), a popul ...
cultivated maize in numerous varieties throughout
Mesoamerica
Mesoamerica is a historical region and cultural area in southern North America and most of Central America. It extends from approximately central Mexico through Belize, Guatemala, El Salvador, Honduras, Nicaragua, and northern Costa Rica ...
; they cooked, ground and processed it through
nixtamalization
Nixtamalization () is a process for the preparation of corn, or other grain, in which the grain is soaked and cooked in an alkaline solution, usually limewater (but sometimes aqueous alkali metal carbonates), washed, and then hulled. The ter ...
. It was believed that beginning about 2500 BC, the crop spread through much of the Americas. Research of the 21st century has established even earlier dates. The region developed a trade network based on surplus and varieties of maize crops.
Mapuche
The Mapuche ( (Mapuche & Spanish: )) are a group of indigenous inhabitants of south-central Chile and southwestern Argentina, including parts of Patagonia. The collective term refers to a wide-ranging ethnicity composed of various groups who s ...
quinoa
Quinoa (''Chenopodium quinoa''; , from Quechua ' or ') is a flowering plant in the amaranth family. It is a herbaceous annual plant grown as a crop primarily for its edible seeds; the seeds are rich in protein, dietary fiber, B vitamins, a ...
pre-Hispanic
In the history of the Americas, the pre-Columbian era spans from the original settlement of North and South America in the Upper Paleolithic period through European colonization, which began with Christopher Columbus's voyage of 1492. Usually, th ...
times; however, potato was the staple food of most Mapuches, "specially in the southern and coastal apucheterritories where maize did not reach maturity". Before the expansion of the
Inca Empire
The Inca Empire (also known as the Incan Empire and the Inka Empire), called ''Tawantinsuyu'' by its subjects, ( Quechua for the "Realm of the Four Parts", "four parts together" ) was the largest empire in pre-Columbian America. The adm ...
maize was traded and transported as far south as 40°19' S in Melinquina,
Lácar Department
Lácar is a department located in the south of Neuquén Province, Argentina.
Geography
The Department limits with Huiliches Department at North, Collón Cura Department at northeast, Rio Negro Province at southeast, Los Lagos Department at ...
. In that location maize remains were found inside pottery dated to 730 ± 80 BP and 920 ± 60 BP. Probably this maize was brought across the Andes from Chile. The presence of maize in
Guaitecas Archipelago
Guaitecas Archipelago is a sparsely populated archipelago in the Aisén region of Chile. The archipelago is made up of eight main islands and numerous smaller ones. The eight largest islands are from northwest to southeast: Gran Guaiteca, Ascenc ...
(43°55' S), the southernmost outpost of pre-Hispanic agriculture, is reported by early Spanish explorers. However the Spanish may have misidentified the plant.
By at least 1000 BCE, the
Olmec
The Olmecs () were the earliest known major Mesoamerican civilization. Following a progressive development in Soconusco, they occupied the tropical lowlands of the modern-day Mexican states of Veracruz and Tabasco. It has been speculated that ...
in
Mesoamerica
Mesoamerica is a historical region and cultural area in southern North America and most of Central America. It extends from approximately central Mexico through Belize, Guatemala, El Salvador, Honduras, Nicaragua, and northern Costa Rica ...
had based their calendar, language, myths and worldview with maize at the center of their symbolism.
Columbian exchange
After the arrival of Europeans in 1492, Spanish settlers consumed maize, and explorers and traders carried it back to Europe and introduced it to other countries. Spanish settlers much preferred
wheat
Wheat is a grass widely cultivated for its seed, a cereal grain that is a worldwide staple food. The many species of wheat together make up the genus ''Triticum'' ; the most widely grown is common wheat (''T. aestivum''). The archaeologi ...
bread to maize,
cassava
''Manihot esculenta'', commonly called cassava (), manioc, or yuca (among numerous regional names), is a woody shrub of the spurge family, Euphorbiaceae, native to South America. Although a perennial plant, cassava is extensively cultivated ...
, or potatoes. Maize flour could not be substituted for wheat for communion bread, since in Christian belief only wheat could undergo
transubstantiation
Transubstantiation (Latin: ''transubstantiatio''; Greek: μετουσίωσις '' metousiosis'') is, according to the teaching of the Catholic Church, "the change of the whole substance of bread into the substance of the Body of Christ and of ...
and be transformed into the body of Christ. Some Spaniards worried that by eating indigenous foods, which they did not consider nutritious, they would weaken and risk turning into Indians. "In the view of Europeans, it was the food they ate, even more than the environment in which they lived, that gave Amerindians and Spaniards both their distinctive physical characteristics and their characteristic personalities." Despite these worries, Spaniards did consume maize. Archeological evidence from Florida sites indicate they cultivated it as well.Earle, ''The Body of the Conquistador'', p. 144.
Maize spread to the rest of the world because of its ability to grow in diverse climates. It was cultivated in Spain just a few decades after Columbus's voyages and then spread to Italy, West Africa and elsewhere.
Widespread cultivation most likely began in southern Spain in 1525, after which it quickly spread to the rest of the
Spanish Empire
The Spanish Empire ( es, link=no, Imperio español), also known as the Hispanic Monarchy ( es, link=no, Monarquía Hispánica) or the Catholic Monarchy ( es, link=no, Monarquía Católica) was a colonial empire governed by Spain and its prede ...
including its territories in Italy (and, from there, to other Italian states). Maize had many advantages over wheat and barley; it yielded two and a half times the
food energy
Food energy is chemical energy that animals (including humans) derive from their food to sustain their metabolism, including their muscular activity.
Most animals derive most of their energy from aerobic respiration, namely combining the carbohy ...
per unit cultivated area, could be harvested in successive years from the same plot of land, and grew in wildly varying altitudes and climates, from relatively dry regions with only of annual rainfall to damp regions with over . By the 17th century it was a common peasant food in Southwestern Europe, including Portugal, Spain, southern France, and Italy. By the 18th century, it was the chief food of the southern French and Italian peasantry, especially in the form of polenta in Italy.
Names
The word ''maize'' derives from the Spanish form of the indigenous
Taíno
The Taíno were a historic indigenous people of the Caribbean whose culture has been continued today by Taíno descendant communities and Taíno revivalist communities. At the time of European contact in the late 15th century, they were the pri ...
word for the plant, ''mahiz''. Using the maize common name, Linnaeus included it as the species epithet in ''Zea mays''. It is known by other names including "corn" in some English speaking countries.
''Maize'' is preferred in formal, scientific, and international usage as a common name because it refers specifically to this one grain, unlike ''corn'', which has a complex variety of meanings that vary by context and geographic region. International groups such as the Centre for Agriculture and Bioscience International also consider maize the preferred common name. According to Ohio State University, the US and a handful of other English-speaking countries primarily use corn, but the rest of the world calls this maize or maíz. The word maize is considered interchangeable with corn in
the West
West is a cardinal direction or compass point.
West or The West may also refer to:
Geography and locations
Global context
* The Western world
* Western culture and Western civilization in general
* The Western Bloc, countries allied with NATO ...
; during early British and American trade, all grains were considered corn. Maize retained the name corn in the West as the primary grain in these trade relationships.
The word "corn" outside the US, Canada, Australia, and New Zealand is synonymous with grain referring to any cereal crop with its meaning understood to vary geographically to refer to the local staple. In the United States, Canada, Australia, and New Zealand, ''corn'' primarily means maize; this usage started as a shortening of "Indian corn". "Indian corn" primarily means maize (the staple grain of indigenous Americans), but can refer more specifically to multicolored " flint corn" used for decoration. Other common names include barajovar, makka, silk maize, and zea.
In a 1999 journal article, Betty Fussell describing calling maize as corn was "to plunge into tragi-farcial mistranslations of language and history." Similar to the British, the Spanish referred to maize as panizo, a generic term for cereal grains, as did Italians with the term polenta. The British later referred to maize as Turkey wheat, Turkey corn, or Indian corn with Fusell commenting that "they meant not a place but a condition, a savage rather than a civilized grain", especially with
Turkish people
The Turkish people, or simply the Turks ( tr, Türkler), are the world's largest Turkic ethnic group; they speak various dialects of the Turkish language and form a majority in Turkey and Northern Cyprus. In addition, centuries-old ethnic ...
later naming it kukuruz, or barbaric.
The word ''maize'' is used by agricultural bodies and research institutes such as the UN's
FAO
The Food and Agriculture Organization of the United Nations (FAO)french: link=no, Organisation des Nations unies pour l'alimentation et l'agriculture; it, Organizzazione delle Nazioni Unite per l'Alimentazione e l'Agricoltura is an intern ...
, the
International Maize and Wheat Improvement Center
The International Maize and Wheat Improvement Center (known - even in English - by its Spanish acronym CIMMYT for ''Centro Internacional de Mejoramiento de Maíz y Trigo'') is a non-profit research-for-development organization that develops im ...
based out of Mexico, and the Indian Institute of Maize Research. National agricultural and industry associations often include the word ''maize'' in their name such as the Maize Association of Australia, and the National Maize Association of Nigeria.
In Southern Africa, maize is commonly called ''mielie'' (
Afrikaans
Afrikaans (, ) is a West Germanic language that evolved in the Dutch Cape Colony from the Dutch vernacular of Holland proper (i.e., the Hollandic dialect) used by Dutch, French, and German settlers and their enslaved people. Afrikaans gra ...
) or ''mealie'' (English), words possibly derived from the Portuguese word for maize, ''milho'', but more probably from Dutch ''meel'' or English ''meal'', meaning the edible part of a grain or
pulse
In medicine, a pulse represents the tactile arterial palpation of the cardiac cycle (heartbeat) by trained fingertips. The pulse may be palpated in any place that allows an artery to be compressed near the surface of the body, such as at the n ...
.
Structure and physiology
The maize plant is often in height, though some natural strains can grow , and the tallest recorded plant reached almost . The stem is commonly composed of 20
internodes
A stem is one of two main structural axes of a vascular plant, the other being the root. It supports leaves, flowers and fruits, transports water and dissolved substances between the roots and the shoots in the xylem and phloem, stores nutrien ...
of length. The leaves arise from the nodes, alternately on opposite sides on the stalk, and have
entire margin
This glossary of botanical terms is a list of definitions of terms and concepts relevant to botany and plants in general. Terms of plant morphology are included here as well as at the more specific Glossary of plant morphology and Glossary o ...
s.
The apex of the stem ends in the tassel, an
inflorescence
An inflorescence is a group or cluster of flowers arranged on a Plant stem, stem that is composed of a main branch or a complicated arrangement of branches. Morphology (biology), Morphologically, it is the modified part of the shoot of sperma ...
of male flowers. When the tassel is mature and conditions are suitably warm and dry, anthers on the tassel
dehisce
Dehiscence is the splitting of a mature plant structure along a built-in line of weakness to release its contents. This is common among fruits, anthers and sporangia. Sometimes this involves the complete detachment of a part; structures that op ...
and release pollen. Maize pollen is
anemophilous
Anemophily or wind pollination is a form of pollination whereby pollen is distributed by wind. Almost all gymnosperms are anemophilous, as are many plants in the order Poales, including grasses, sedges, and rushes. Other common anemophilous plan ...
(dispersed by wind), and because of its large settling velocity, most pollen falls within a few meters of the tassel.
Ears develop above a few of the leaves in the midsection of the plant, between the stem and leaf sheath, elongating by around per day, to a length of with being the maximum alleged in the subspecies. They are female
inflorescence
An inflorescence is a group or cluster of flowers arranged on a Plant stem, stem that is composed of a main branch or a complicated arrangement of branches. Morphology (biology), Morphologically, it is the modified part of the shoot of sperma ...
s, tightly enveloped by several layers of ear leaves commonly called husks.
Elongated stigmas, called silks, emerge from the whorl of husk leaves at the end of the ear. They are often pale yellow and in length, like tufts of hair in appearance. At the end of each is a carpel, which may develop into a "kernel" if fertilized by a pollen grain. The
pericarp
Fruit anatomy is the plant anatomy of the internal structure of fruit. Fruits are the mature ovary or ovaries of one or more flowers. They are found in three main anatomical categories: aggregate fruits, multiple fruits, and simple fruits. Aggr ...
of the fruit is fused with the seed coat referred to as "
caryopsis
In botany, a caryopsis (plural caryopses) is a type of simple fruit—one that is monocarpellate (formed from a single carpel) and indehiscent (not opening at maturity) and resembles an achene, except that in a caryopsis the pericarp is fuse ...
", typical of the
grasses
Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns ...
, and the entire kernel is often referred to as the "
seed
A seed is an embryonic plant enclosed in a protective outer covering, along with a food reserve. The formation of the seed is a part of the process of reproduction in seed plants, the spermatophytes, including the gymnosperm and angiospe ...
". The cob is close to a multiple fruit in structure, except that the individual fruits (the kernels) never fuse into a single mass. The grains are about the size of peas, and adhere in regular rows around a white, pithy substance, which forms the cob. The maximum size of kernels is reputedly . An ear commonly holds 600 kernels. They are of various colors: blackish,
bluish-gray
''Glaucous'' (, ) is used to describe the pale grey or bluish-green appearance of the surfaces of some plants, as well as in the names of birds, such as the glaucous gull (''Larus hyperboreus''), glaucous-winged gull (''Larus glaucescens''), gl ...
,
purple
Purple is any of a variety of colors with hue between red and blue. In the RGB color model used in computer and television screens, purples are produced by mixing red and blue light. In the RYB color model historically used by painters, ...
, green, red, white and yellow. When ground into flour, maize yields more flour with much less
bran
Bran, also known as miller's bran, is the hard outer layers of cereal grain. It consists of the combined aleurone and pericarp. Corn (maize) bran also includes the pedicel (tip cap). Along with germ, it is an integral part of whole grains, ...
than wheat does. It lacks the protein
gluten
Gluten is a structural protein naturally found in certain cereal grains. Although "gluten" often only refers to wheat proteins, in medical literature it refers to the combination of prolamin and glutelin proteins naturally occurring in all grai ...
of wheat and, therefore, makes baked goods with poor rising capability. A genetic variant that accumulates more sugar and less starch in the ear is consumed as a vegetable and is called sweet corn. Young ears can be consumed raw, with the cob and silk, but as the plant matures (usually during the summer months), the cob becomes tougher and the silk dries to inedibility. By the end of the growing season, the kernels dry out and become difficult to chew without cooking.
File:Cornsilk 7091.jpg, Female inflorescence, with young
silk
Silk is a natural protein fiber, some forms of which can be woven into textiles. The protein fiber of silk is composed mainly of fibroin and is produced by certain insect larvae to form cocoons. The best-known silk is obtained from the ...
File:Corn blooming.jpg, Mature silk
File:GreenCorn.JPG, Stalks, ears and silk
File:Männliche Blüte einer Maispflanze 2009-08-19.JPG, Male flowers
File:ZeaMays.jpg, Full-grown maize plants
File:Klip kukuruza uzgojen u Međimurju (Croatia).JPG, Mature maize ear on a stalk
Planting density affects multiple aspects of maize. Modern farming techniques in
developed countries
A developed country (or industrialized country, high-income country, more economically developed country (MEDC), advanced country) is a sovereign state that has a high quality of life, developed economy and advanced technological infrastruct ...
usually rely on dense planting, which produces one ear per stalk. Stands of
silage
Silage () is a type of fodder made from green foliage crops which have been preserved by fermentation to the point of acidification. It can be fed to cattle, sheep and other such ruminants (cud-chewing animals). The fermentation and storage ...
maize are yet denser, and achieve a lower percentage of ears and more plant matter.
Maize is a facultative short-day plant and flowers in a certain number of
growing degree day
Growing degree days (GDD), also called growing degree units (GDUs), are a heuristic tool in phenology. GDD are a measure of heat accumulation used by horticulturists, gardeners, and farmers to predict plant and animal development rates such as the ...
s > in the environment to which it is adapted. The magnitude of the influence that long nights have on the number of days that must pass before maize
flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...
s is genetically prescribed and regulated by the
phytochrome
Phytochromes are a class of photoreceptor in plants, bacteria and fungi used to detect light. They are sensitive to light in the red and far-red region of the visible spectrum and can be classed as either Type I, which are activated by far-re ...
cultivar
A cultivar is a type of cultivated plant that people have selected for desired traits and when propagated retain those traits. Methods used to propagate cultivars include: division, root and stem cuttings, offsets, grafting, tissue culture ...
s such that the long days characteristic of higher latitudes allow the plants to grow so tall that they do not have enough time to produce seed before being killed by frost. These attributes, however, may prove useful in using tropical maize for biofuels.
Immature maize shoots accumulate a powerful antibiotic substance, 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one ( DIMBOA). DIMBOA is a member of a group of
hydroxamic acid
A hydroxamic acid is a class of organic compounds bearing the functional group RC(O)N(OH)R', with R and R' as organic residues and CO as a carbonyl group. They are amides (RC(O)NHR') wherein the NH center has an OH substitution. They are often us ...
s (also known as benzoxazinoids) that serve as a natural defense against a wide range of pests, including insects, pathogenic fungi and
bacteria
Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one Cell (biology), biological cell. They constitute a large domain (biology), domain of prokaryotic microorganisms. Typically a few micrometr ...
. DIMBOA is also found in related grasses, particularly wheat. A maize mutant (bx) lacking DIMBOA is highly susceptible to attack by
aphid
Aphids are small sap-sucking insects and members of the superfamily Aphidoidea. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white woolly aphids. A t ...
s and
fungi
A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...
. DIMBOA is also responsible for the relative resistance of immature maize to the
European corn borer
The European corn borer (''Ostrinia nubilalis''), also known as the European corn worm or European high-flyer, is a moth of the family Crambidae which includes other grass moths. It is a pest of grain, particularly maize (''Zea mays''). The in ...
(family
Crambidae
The Crambidae are the grass moth family of lepidopterans. They are variable in appearance, the nominal subfamily Crambinae (grass moths) taking up closely folded postures on grass stems where they are inconspicuous, while other subfamilies includ ...
). As maize matures, DIMBOA levels and resistance to the corn borer decline.
Because of its shallow roots, maize is susceptible to droughts, intolerant of nutrient-deficient soils, and prone to be uprooted by severe winds.
File:Ab food 06.jpg, Maize kernels
File:Maize plant diagram.svg, Maize plant diagram
File:Aa maize ear irregular 01.jpg, Ear of maize with irregular rows of kernels
While yellow maizes derive their color from
zeaxanthin
Zeaxanthin is one of the most common carotenoids in nature, and is used in the xanthophyll cycle. Synthesized in plants and some micro-organisms, it is the pigment that gives paprika (made from bell peppers), corn, saffron, goji ( wolfberries ...
, in red-colored maizes, the kernel coloration is due to anthocyanins and
phlobaphene
Phlobaphenes (or phlobaphens, CAS No.:71663-19-9) are reddish, alcohol-soluble and water-insoluble phenolic substances. They can be extracted from plants, or be the result from treatment of tannin extracts with mineral acids (tanner's red). The nam ...
s. These latter substances are synthesized in the flavonoids synthetic pathway from polymerization of
flavan-4-ol
The flavan-4-ols (3-deoxyflavonoids) are flavone-derived alcohols and a family of flavonoids. Flavan-4-ols are colorless precursor compounds that polymerize to form red phlobaphene pigments. They can be found in the sorghum. Glycosides (abacopteri ...
s by the expression of maize pericarp color1 (p1) gene which encodes an R2R3
myb
MyB (Hangul: 마이비) was a South Korean girl group formed by Maroo Entertainment. The group debuted on August 25, 2015 with ''My Oh My'' and made a comeback on November 13, 2015 with ''Ddoddo'', before the group officially disbanded on December ...
-like
transcriptional activator
A transcriptional activator is a protein (transcription factor) that increases transcription of a gene or set of genes. Activators are considered to have ''positive'' control over gene expression, as they function to promote gene transcription and ...
of the A1 gene encoding for the
dihydroflavonol 4-reductase
In enzymology, a dihydrokaempferol 4-reductase () is an enzyme that catalyzes the chemical reaction
:cis-3,4-leucopelargonidin + NADP+ \rightleftharpoons (+)-dihydrokaempferol + NADPH + H+
Thus, the two substrates of this enzyme are cis-3,4 ...
(reducing
dihydroflavonol
The flavanonols (with two "o"s a.k.a. 3-hydroxyflavanone or 2,3-dihydroflavonol) are a class of flavonoids that use the 3-hydroxy-2,3-dihydro-2-phenylchromen-4-one (IUPAC name) backbone.
Some examples include:
* Taxifolin (or Dihydroquercetin)
* ...
s into flavan-4-ols) while another gene (Suppressor of Pericarp Pigmentation 1 or SPP1) acts as a
suppressor
A silencer, also known as a sound suppressor, suppressor, or sound moderator, is a muzzle device that reduces the acoustic intensity of the muzzle report (sound of a gunshot) and muzzle rise when a gun (firearm or air gun) is discharged, b ...
. The p1 gene encodes an Myb-homologous transcriptional activator of genes required for biosynthesis of red phlobaphene pigments, while the P1-wr allele specifies colorless kernel pericarp and red cobs, and unstable factor for orange1 (Ufo1) modifies P1-wr expression to confer pigmentation in kernel pericarp, as well as vegetative tissues, which normally do not accumulate significant amounts of phlobaphene pigments. The maize P gene encodes a Myb homolog that recognizes the sequence CCT/AACC, in sharp contrast with the C/TAACGG bound by vertebrate Myb proteins.
The ''ear leaf'' is the leaf most closely associated with a particular developing ear. This leaf and above contribute 70% to 75% to 90% of grain fill. Therefore fungicide application is most important in that region in most disease environments.
Abnormal flowers
Maize flowers may sometimes exhibit mutations that lead to the formation of female flowers in the tassel. These mutations, ''ts4'' and ''Ts6'', prohibit the development of the stamen while simultaneously promoting pistil development. This may cause
inflorescence
An inflorescence is a group or cluster of flowers arranged on a Plant stem, stem that is composed of a main branch or a complicated arrangement of branches. Morphology (biology), Morphologically, it is the modified part of the shoot of sperma ...
s containing both male and female flowers, or hermaphrodite flowers.
Genetics
Maize is an annual grass in the family
Gramineae
Poaceae () or Gramineae () is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos and the grasses of natural grassland and species cultivated in lawns and ...
, which includes such plants as
wheat
Wheat is a grass widely cultivated for its seed, a cereal grain that is a worldwide staple food. The many species of wheat together make up the genus ''Triticum'' ; the most widely grown is common wheat (''T. aestivum''). The archaeologi ...
barley
Barley (''Hordeum vulgare''), a member of the grass family, is a major cereal grain grown in temperate climates globally. It was one of the first cultivated grains, particularly in Eurasia as early as 10,000 years ago. Globally 70% of barley p ...
,
rice
Rice is the seed of the grass species '' Oryza sativa'' (Asian rice) or less commonly ''Oryza glaberrima'' (African rice). The name wild rice is usually used for species of the genera '' Zizania'' and '' Porteresia'', both wild and domesticat ...
, sorghum, and sugarcane. There are two major species of the genus '' Zea'' (out of six total): ''Z. mays'' (maize) and '' Z. diploperennis'', which is a
perennial
A perennial plant or simply perennial is a plant that lives more than two years. The term ('' per-'' + '' -ennial'', "through the years") is often used to differentiate a plant from shorter-lived annuals and biennials. The term is also wid ...
type of teosinte. The
annual
Annual may refer to:
*Annual publication, periodical publications appearing regularly once per year
** Yearbook
** Literary annual
*Annual plant
*Annual report
*Annual giving
*Annual, Morocco, a settlement in northeastern Morocco
*Annuals (band), ...
teosinte variety called '' Z. m. mexicana'' is the closest botanical relative to maize. It still grows in the wild as an annual in Mexico and Guatemala.
Many forms of maize are used for food, sometimes classified as various subspecies related to the amount of starch each has:
* Flour corn: ''Z. m.'' var. ''amylacea''
* Popcorn: ''Z. m.'' var. ''everta''
* Dent corn : ''Z. m.'' var. ''indentata''
* Flint corn: ''Z. m.'' var. ''indurata''
* Sweet corn: ''Z. m.'' var. ''saccharata'' and ''Z. m.'' var. ''rugosa''
*
Waxy corn
Waxy may refer to:
* a substance related to wax
* colloquially for a waxworm (particularly used by anglers)
* Waxy (band), an American stoner rock band
* Waxy (horse), a thoroughbred racehorse
* WAXY (AM), a radio station (790 AM) licensed to se ...
: ''Z. m.'' var. ''ceratina''
* Amylomaize: ''Z. mays''
* Pod corn: ''Z. m.'' var. ''tunicata'' Larrañaga ex A. St. Hil.
* Striped maize: ''Z. m.'' var. ''japonica''
This system has been replaced (though not entirely displaced) over the last 60 years by multivariable classifications based on ever more data.
Agronomic
Agricultural economics is an applied field of economics concerned with the application of economic theory in optimizing the production and distribution of food and fiber products.
Agricultural economics began as a branch of economics that spe ...
data were supplemented by botanical traits for a robust initial classification, then genetic, cytological, protein and DNA evidence was added. Now, the categories are forms (little used), races, racial complexes, and recently branches.
Maize is a diploid with 20
chromosome
A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins are ...
s (n=10). The combined length of the chromosomes is 1500 cM. Some of the maize chromosomes have what are known as "chromosomal knobs": highly repetitive
heterochromatic
Heterochromia is a variation in coloration. The term is most often used to describe color differences of the iris, but can also be applied to color variation of hair or skin. Heterochromia is determined by the production, delivery, and concentra ...
domains that stain darkly. Individual knobs are polymorphic among strains of both maize and teosinte.
Barbara McClintock used these knob markers to validate her
transposon
A transposable element (TE, transposon, or jumping gene) is a nucleic acid sequence in DNA that can change its position within a genome, sometimes creating or reversing mutations and altering the cell's genetic identity and genome size. Tra ...
theory of "jumping genes", for which she won the 1983
Nobel Prize in Physiology or Medicine
The Nobel Prize in Physiology or Medicine is awarded yearly by the Nobel Assembly at the Karolinska Institute for outstanding discoveries in physiology or medicine. The Nobel Prize is not a single prize, but five separate prizes that, accord ...
centromere
The centromere links a pair of sister chromatids together during cell division. This constricted region of chromosome connects the sister chromatids, creating a short arm (p) and a long arm (q) on the chromatids. During mitosis, spindle fibers ...
s have two types of structural components, both of which are found only in the centromeres: Large arrays of CentC, a short
satellite DNA Satellite DNA consists of very large arrays of tandemly repeating, non-coding DNA. Satellite DNA is the main component of functional centromeres, and form the main structural constituent of heterochromatin.
The name "satellite DNA" refers to the ...
; and a few of a family of
retrotransposon
Retrotransposons (also called Class I transposable elements or transposons via RNA intermediates) are a type of genetic component that copy and paste themselves into different genomic locations (transposon) by converting RNA back into DNA through ...
s. The
B chromosome
In addition to the normal karyotype, wild populations of many animal, plant, and fungi species contain B chromosomes (also known as supernumerary, accessory, (conditionally-)dispensable, or lineage-specific chromosomes). By definition, these chro ...
, unlike the others, contains an additional repeat which extends into neighboring areas of the chromosome. Centromeres can accidentally shrink during division and still function, although it is thought this will fail if it shrinks below a few hundred kilobase.
Kinetochore
A kinetochore (, ) is a disc-shaped protein structure associated with duplicated chromatids in eukaryotic cells where the spindle fibers attach during cell division to pull sister chromatids apart. The kinetochore assembles on the centromere and ...
s contain RNA originating from centromeres. Centromere regions can become inactive, and can continue in that state if the chromosome still has another active one.
The Maize Genetics Cooperation Stock Center, funded by the USDA Agricultural Research Service and located in the Department of Crop Sciences at the
University of Illinois at Urbana-Champaign
The University of Illinois Urbana-Champaign (U of I, Illinois, University of Illinois, or UIUC) is a public land-grant research university in Illinois in the twin cities of Champaign and Urbana. It is the flagship institution of the Univ ...
, is a stock center of maize mutants. The total collection has nearly 80,000 samples. The bulk of the collection consists of several hundred named genes, plus additional gene combinations and other heritable variants. There are about 1000 chromosomal aberrations (e.g., translocations and inversions) and stocks with abnormal chromosome numbers (e.g.,
tetraploid
Polyploidy is a condition in which the cells of an organism have more than one pair of ( homologous) chromosomes. Most species whose cells have nuclei (eukaryotes) are diploid, meaning they have two sets of chromosomes, where each set contains ...
s). Genetic data describing the maize mutant stocks as well as myriad other data about maize genetics can be accessed a MaizeGDB the Maize Genetics and Genomics Database.
In 2005, the US
National Science Foundation
The National Science Foundation (NSF) is an independent agency of the United States government that supports fundamental research and education in all the non-medical fields of science and engineering. Its medical counterpart is the National ...
(NSF), Department of Agriculture (
USDA
The United States Department of Agriculture (USDA) is the federal executive department responsible for developing and executing federal laws related to farming, forestry, rural economic development, and food. It aims to meet the needs of com ...
) and the
Department of Energy A Ministry of Energy or Department of Energy is a government department in some countries that typically oversees the production of fuel and electricity; in the United States, however, it manages nuclear weapons development and conducts energy-re ...
(DOE) formed a consortium to sequence the B73 maize
genome
In the fields of molecular biology and genetics, a genome is all the genetic information of an organism. It consists of nucleotide sequences of DNA (or RNA in RNA viruses). The nuclear genome includes protein-coding genes and non-coding g ...
. The resulting DNA sequence data was deposited immediately into
GenBank
The GenBank sequence database is an open access, annotated collection of all publicly available nucleotide sequences and their protein translations. It is produced and maintained by the National Center for Biotechnology Information (NCBI; a part ...
, a public repository for genome-sequence data. Sequences and genome annotations have also been made available throughout the project's lifetime at the project's official site.
Primary sequencing of the maize genome was completed in 2008. On November 20, 2009, the consortium published results of its sequencing effort in ''Science''. The genome, 85% of which is composed of
transposon
A transposable element (TE, transposon, or jumping gene) is a nucleic acid sequence in DNA that can change its position within a genome, sometimes creating or reversing mutations and altering the cell's genetic identity and genome size. Tra ...
s, was found to contain 32,540 genes (By comparison, the
human genome
The human genome is a complete set of nucleic acid sequences for humans, encoded as DNA within the 23 chromosome pairs in cell nuclei and in a small DNA molecule found within individual mitochondria. These are usually treated separately as the ...
contains about 2.9 billion bases and 26,000 genes). Much of the maize genome has been duplicated and reshuffled by helitrons—group of
rolling circle
Rolling circle replication (RCR) is a process of unidirectional nucleic acid replication that can rapidly synthesize multiple copies of circular molecules of DNA or RNA, such as plasmids, the genomes of bacteriophages, and the circular RNA geno ...
transposons.
In ''Z. mays'' and various other angiosperms the
MADS-box
The MADS box is a conserved sequence motif. The genes which contain this motif are called the MADS-box gene family. The MADS box encodes the DNA-binding MADS domain. The MADS domain binds to DNA sequences of high similarity to the motif CC /Tsub>6G ...
motif is involved in floral development. Early study in several angiosperm models including ''Z. mays'' was the beginning of research into the molecular evolution of floral structure in general, as well as their role in nonflowering plants.
Varieties differ in their resistance to insects, including borers.CIMMYT maintains a large collection of maize/corn accessions tested and cataloged for insect resistance.
Evolution
As with many plants and animals, ''Z. mays'' has a positive correlation between
effective population size
The effective population size (''N'e'') is a number that, in some simplified scenarios, corresponds to the number of breeding individuals in the population. More generally, ''N'e'' is the number of individuals that an idealised population w ...
and the magnitude of
selection pressure
Any cause that reduces or increases reproductive success in a portion of a population potentially exerts evolutionary pressure, selective pressure or selection pressure, driving natural selection. It is a quantitative description of the amount of ...
. ''Z. m.'' having an EPS of ~650,000, it clusters with others of about the same EPS, and has 79% of its
amino acid
Amino acids are organic compounds that contain both amino and carboxylic acid functional groups. Although hundreds of amino acids exist in nature, by far the most important are the alpha-amino acids, which comprise proteins. Only 22 alpha a ...
sites under selection.Recombination is a significant source of
diversity
Diversity, diversify, or diverse may refer to:
Business
*Diversity (business), the inclusion of people of different identities (ethnicity, gender, age) in the workforce
*Diversity marketing, marketing communication targeting diverse customers
* ...
in ''Z. mays''. (Note that this finding supersedes previous studies which showed no such correlation.)
This recombination/diversity effect is seen throughout plants but is also found to not occur – or not as strongly – in regions of high gene density. This is likely the reason that domesticated ''Z. mays'' has not seen as much of an increase in diversity within areas of higher density as in regions of lower density, although there is more evidence in other plants.
Some lines of maize have undergone ancient
polyploid
Polyploidy is a condition in which the cells of an organism have more than one pair of ( homologous) chromosomes. Most species whose cells have nuclei ( eukaryotes) are diploid, meaning they have two sets of chromosomes, where each set contain ...
y events, starting 11m years ago. Over that time ~72% of polyploid duplicated genes have been retained, which is higher than other plants with older polyploidy events. Thus maize ''may'' be due to lose more duplicate genes as time goes along, similar to the course followed by the genomes of other plants. If so - if gene loss has merely not occurred yet - that could explain the lack of observed positive selection and lower negative selection which are observed in otherwise similar plants, i.e. also naturally
outcrossing
Out-crossing or out-breeding is the technique of crossing between different breeds. This is the practice of introducing distantly related genetic material into a breeding line, thereby increasing genetic diversity.
Outcrossing can be a usefu ...
and with similar effective population sizes.
Ploidy does not appear to influence EPS or magnitude of selection effect in maize.
Breeding
Maize reproduces sexually each year. This randomly selects half the genes from a given plant to propagate to the next generation, meaning that desirable traits found in the crop (like high yield or good nutrition) can be lost in subsequent generations unless certain techniques are used.
Maize breeding in prehistory resulted in large plants producing large ears. Modern breeding began with individuals who selected highly productive varieties in their fields and then sold seed to other farmers. James L. Reid was one of the earliest and most successful developing Reid's Yellow Dent in the 1860s. These early efforts were based on mass selection. Later breeding efforts included ear to row selection (C. G. Hopkins c. 1896), hybrids made from selected
inbred
Inbreeding is the production of offspring from the mating or breeding of individuals or organisms that are closely related genetically. By analogy, the term is used in human reproduction, but more commonly refers to the genetic disorders and o ...
lines (G. H. Shull, 1909), and the highly successful double cross hybrids using four inbred lines ( D. F. Jones c. 1918, 1922). University supported breeding programs were especially important in developing and introducing modern hybrids. By the 1930s, companies such as
Pioneer
Pioneer commonly refers to a settler who migrates to previously uninhabited or sparsely inhabited land.
In the United States pioneer commonly refers to an American pioneer, a person in American history who migrated west to join in settling and de ...
devoted to production of hybrid maize had begun to influence long-term development. Internationally important seed banks such as the
International Maize and Wheat Improvement Center
The International Maize and Wheat Improvement Center (known - even in English - by its Spanish acronym CIMMYT for ''Centro Internacional de Mejoramiento de Maíz y Trigo'') is a non-profit research-for-development organization that develops im ...
(CIMMYT) and the US bank at the Maize Genetics Cooperation Stock Center
University of Illinois at Urbana-Champaign
The University of Illinois Urbana-Champaign (U of I, Illinois, University of Illinois, or UIUC) is a public land-grant research university in Illinois in the twin cities of Champaign and Urbana. It is the flagship institution of the Univ ...
maintain
germplasm
Germplasm are living genetic resources such as seeds or tissues that are maintained for the purpose of animal and plant breeding, preservation, and other research uses. These resources may take the form of seed collections stored in seed banks, t ...
important for future crop development.
Since the 1940s the best strains of maize have been first-generation hybrids made from inbred strains that have been optimized for specific traits, such as yield, nutrition, drought, pest and disease tolerance. Both conventional cross-breeding and genetic engineering have succeeded in increasing output and reducing the need for cropland, pesticides, water and fertilizer. There is conflicting evidence to support the hypothesis that maize yield potential has increased over the past few decades. This suggests that changes in yield potential are associated with leaf angle, lodging resistance, tolerance of high plant density, disease/pest tolerance, and other agronomic traits rather than increase of yield potential per individual plant.
Certain varieties of maize have been bred to produce many ears which are the source of the "
baby corn
An infant or baby is the very young offspring of human beings. ''Infant'' (from the Latin word ''infans'', meaning 'unable to speak' or 'speechless') is a formal or specialised synonym for the common term ''baby''. The terms may also be used to ...
" used as a vegetable in
Asian cuisine
Asian cuisine includes several major regional cuisines: Central Asian, East Asian, North Asian, South Asian, Southeast Asian, and West Asian. A cuisine is a characteristic style of cooking practices and traditions, usually associated with ...
.
CIMMYT operates a conventional breeding program to provide optimized strains. The program began in the 1980s. Hybrid seeds are distributed in Africa by the Drought Tolerant Maize for Africa project.
Genetic engineering
Genetically engineered
Genetic engineering, also called genetic modification or genetic manipulation, is the modification and manipulation of an organism's genes using technology. It is a set of technologies used to change the genetic makeup of cells, including t ...
(GE) maize was one of the 26 GE crops grown commercially in 2016. The vast majority of this is
Bt maize
Genetically modified maize (corn) is a genetically modified crop. Specific maize strains have been genetically engineered to express agriculturally-desirable traits, including resistance to pests and to herbicides. Maize strains with both trait ...
. Grown since 1997 in the United States and Canada, 92% of the US maize crop was genetically modified in 2016 and 33% of the worldwide maize crop was GM in 2016. As of 2011, Herbicide-tolerant maize varieties were grown in Argentina, Australia, Brazil, Canada, China, Colombia, El Salvador, the European Union, Honduras, Japan, Korea, Malaysia, Mexico, New Zealand, Philippines, the Russian Federation, Singapore, South Africa, Taiwan, Thailand, and the United States. Insect-resistant maize was grown in Argentina, Australia, Brazil, Canada, Chile, China, Colombia, Egypt, the European Union, Honduras, Japan, Korea, Malaysia, Mexico, New Zealand, Philippines, South Africa, Switzerland, Taiwan, the United States, and Uruguay.
In September 2000, up to $50 million worth of food products were recalled due to the presence of
Starlink
Starlink is a satellite internet constellation operated by SpaceX, providing satellite Internet access coverage to 45 countries. It also aims for global mobile phone service after 2023. SpaceX started launching Starlink satellites in 2019. As ...
genetically modified corn, which had been approved only for animal consumption and had not been approved for human consumption, and was subsequently withdrawn from the market.
For pest and disease resistance
Tropical
landrace
A landrace is a domesticated, locally adapted, often traditional variety of a species of animal or plant that has developed over time, through adaptation to its natural and cultural environment of agriculture and pastoralism, and due to isolatio ...
s remain an important and underused source of resistance alleles for disease and for herbivores. Notable discoveries of rare alleles for this purpose were made by Dao ''et al.'', 2014 and Sood ''et al.'', 2014. Rashid ''et al.'', 2018 use an
association mapping In genetics, association mapping, also known as " linkage disequilibrium mapping", is a method of mapping quantitative trait loci (QTLs) that takes advantage of historic linkage disequilibrium to link phenotypes (observable characteristics) to geno ...
panel from CIMMYT originally developed for tropical drought tolerance traits to find new genomic regions providing sorghum downy mildew resistance, and to further characterize SDMR regions already located by others. .
Origin
Maize is the domesticated variant of teosinte.
* The two plants have dissimilar appearance, maize having a single tall stalk with multiple leaves and teosinte being a short, bushy plant. The difference between the two is largely controlled by differences in just two genes, called grassy tillers-1 (''gt1'', ) and teosinte branched-1 (''tb1'', ).
Several theories had been proposed about the specific origin of maize in Mesoamerica:
# It is a direct
domestication
Domestication is a sustained multi-generational relationship in which humans assume a significant degree of control over the reproduction and care of another group of organisms to secure a more predictable supply of resources from that group. ...
Balsas River
The Balsas River (Spanish Río Balsas, also locally known as the Mezcala River, or Atoyac River) is a major river of south-central Mexico.
The basin flows through the states of Guerrero, México, Morelos, and Puebla. Downstream of Ciudad Alta ...
valley in south-eastern Mexico, with up to 12% of its
genetic material
Nucleic acids are biopolymers, macromolecules, essential to all known forms of life. They are composed of nucleotides, which are the monomers made of three components: a 5-carbon sugar, a phosphate group and a nitrogenous base. The two main clas ...
obtained from ''Z. m.'' ssp. ''mexicana'' through introgression.
# It has been derived from hybridization between a small domesticated maize (a slightly changed form of a wild maize) and a teosinte of section ''Luxuriantes'', either ''Z. luxurians'' or '' Z. diploperennis''.
# It has undergone two or more domestications either of a wild maize or of a teosinte. (The term "teosinte" describes all
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
and subspecies in the genus ''Zea'', excluding ''Z. m.'' ssp. ''mays''.)
# It has evolved from a hybridization of ''Z. diploperennis'' by '' Tripsacum dactyloides''.
In the late 1930s, Paul Mangelsdorf suggested that domesticated maize was the result of a hybridization event between an unknown wild maize and a species of ''
Tripsacum
''Tripsacum'' is a genus of plants in the grass family native to the Western Hemisphere. Gamagrass is a common name for plants in this genus.
Species
formerly included
see '' Anthephora Apluda Chionachne Coelorachis Elionurus Hackeloch ...
'', a related genus. This theory about the origin of maize has been refuted by modern genetic testing, which refutes Mangelsdorf's model and the fourth listed above.
The teosinte origin theory was proposed by the Russian botanist
Nikolai Ivanovich Vavilov
Nikolai Ivanovich Vavilov ( rus, Никола́й Ива́нович Вави́лов, p=nʲɪkɐˈlaj ɪˈvanəvʲɪtɕ vɐˈvʲiləf, a=Ru-Nikolay_Ivanovich_Vavilov.ogg; – 26 January 1943) was a Russian and Soviet agronomist, botanist a ...
in 1931 and the later American
Nobel Prize
The Nobel Prizes ( ; sv, Nobelpriset ; no, Nobelprisen ) are five separate prizes that, according to Alfred Nobel's will of 1895, are awarded to "those who, during the preceding year, have conferred the greatest benefit to humankind." Alfr ...
-winner
George Beadle
George Wells Beadle (October 22, 1903 – June 9, 1989) was an American geneticist. In 1958 he shared one-half of the Nobel Prize in Physiology or Medicine with Edward Tatum for their discovery of the role of genes in regulating biochemical eve ...
in 1932. It is supported experimentally and by recent studies of the plants' genomes. Teosinte and maize can cross-breed and produce fertile offspring. A number of questions remain concerning the species, among them:
# how the immense diversity of the species of sect. ''Zea'' originated,
# how the tiny archaeological specimens of 3500–2700 BC could have been selected from a teosinte, and
# how domestication could have proceeded without leaving remains of teosinte or maize with teosintoid traits earlier than the earliest known until recently, dating from ca. 1100 BC.
The
domestication
Domestication is a sustained multi-generational relationship in which humans assume a significant degree of control over the reproduction and care of another group of organisms to secure a more predictable supply of resources from that group. ...
of maize is of particular interest to researchers— archaeologists,
geneticist
A geneticist is a biologist or physician who studies genetics, the science of genes, heredity, and variation of organisms. A geneticist can be employed as a scientist or a lecturer. Geneticists may perform general research on genetic processes ...
s,
ethnobotanists
Ethnobotany is the study of a region's plants and their practical uses through the traditional knowledge of a local culture and people. An ethnobotanist thus strives to document the local customs involving the practical uses of local flora for m ...
, geographers, etc. The process is thought by some to have started 7,500 to 12,000 years ago. Research from the 1950s to 1970s originally focused on the hypothesis that maize domestication occurred in the highlands between the states of
Oaxaca
Oaxaca ( , also , , from nci, Huāxyacac ), officially the Free and Sovereign State of Oaxaca ( es, Estado Libre y Soberano de Oaxaca), is one of the 32 states that compose the political divisions of Mexico, Federative Entities of Mexico. It is ...
and Jalisco, because the oldest archaeological remains of maize known at the time were found there.
Balsas River
The Balsas River (Spanish Río Balsas, also locally known as the Mezcala River, or Atoyac River) is a major river of south-central Mexico.
The basin flows through the states of Guerrero, México, Morelos, and Puebla. Downstream of Ciudad Alta ...
valley in Mexico's southwestern highlands, and also known as Balsas teosinte, as being the
crop wild relative
A crop wild relative (CWR) is a wild plant closely related to a domesticated plant. It may be a wild ancestor of the domesticated (cultivated) plant or another closely related taxon.
Overview
The wild relatives of crop plants constitute an i ...
that is genetically most similar to modern maize. This was confirmed by further studies, which refined this hypothesis somewhat. Archaeobotanical studies, published in 2009, point to the middle part of the Balsas River valley as the likely location of early domestication; this river is not very long, so these locations are not very distant. Stone milling tools with maize residue have been found in an 8,700 year old layer of deposits in a cave not far from
Iguala, Guerrero
Iguala (), known officially as Iguala de la Independencia, is a historic city located from the state capital of Chilpancingo, in the Mexican state of Guerrero in southwestern Mexico.
Geography
The city of Iguala stands on Federal Highway 95 abo ...
.
Doebley was part of the team that first published, in 2002, that maize had been domesticated only once, about 9,000 years ago, and then spread throughout the Americas.
A primitive corn was being grown in southern Mexico, Central America, and northern South America 7,000 years ago. Archaeological remains of early maize ears, found at Guila Naquitz Cave in the
Oaxaca Valley
The Central Valleys ( es, Valles Centrales) of Oaxaca, also simply known as the Oaxaca Valley, is a geographic region located within the modern-day state of Oaxaca in southern Mexico. In an administrative context, it has been defined as comprising ...
, date back roughly 6,250 years; the oldest ears from caves near Tehuacan, Puebla, 5,450 B.P.
Maize pollen dated to 7,300 B.P. from San Andres, Tabasco, on the Caribbean coast has also been recovered.
As maize was introduced to new cultures, new uses were developed and new varieties selected to better serve in those preparations. Maize was the staple food, or a major staple – along with
squash
Squash may refer to:
Sports
* Squash (sport), the high-speed racquet sport also known as squash racquets
* Squash (professional wrestling), an extremely one-sided match in professional wrestling
* Squash tennis, a game similar to squash but pla ...
, Andean region
potato
The potato is a starchy food, a tuber of the plant ''Solanum tuberosum'' and is a root vegetable native to the Americas. The plant is a perennial in the nightshade family Solanaceae.
Wild potato species can be found from the southern Unit ...
,
quinoa
Quinoa (''Chenopodium quinoa''; , from Quechua ' or ') is a flowering plant in the amaranth family. It is a herbaceous annual plant grown as a crop primarily for its edible seeds; the seeds are rich in protein, dietary fiber, B vitamins, a ...
pre-Columbian
In the history of the Americas, the pre-Columbian era spans from the original settlement of North and South America in the Upper Paleolithic period through European colonization, which began with Christopher Columbus's voyage of 1492. Usually, ...
North American, Mesoamerican, South American, and Caribbean cultures. The Mesoamerican civilization, in particular, was deeply interrelated with maize. Its traditions and rituals involved all aspects of maize cultivation – from the planting to the food preparation. Maize formed the Mesoamerican people's identity.
It is unknown what precipitated its domestication, because the edible portion of the wild variety is too small, and hard to obtain, to be eaten directly, as each kernel is enclosed in a very hard bivalve shell.
In 1939, George Beadle demonstrated that the kernels of teosinte are readily "popped" for human consumption, like modern popcorn. Some have argued it would have taken too many generations of
selective breeding
Selective breeding (also called artificial selection) is the process by which humans use animal breeding and plant breeding to selectively develop particular phenotypic traits (characteristics) by choosing which typically animal or plant m ...
to produce large, compressed ears for efficient cultivation. However, studies of the hybrids readily made by intercrossing teosinte and modern maize suggest this objection is not well founded.
Spreading to the north
Around 4,500 ago, maize began to spread to the north; it was first cultivated in what is now the United States at several sites in New Mexico and Arizona, about 4,100 ago.
During the first millennium AD, maize cultivation spread more widely in the areas north. In particular, the large-scale adoption of maize agriculture and consumption in eastern North America took place about A.D. 900. Native Americans cleared large forest and grassland areas for the new crop.
In 2005, research by the
USDA
The United States Department of Agriculture (USDA) is the federal executive department responsible for developing and executing federal laws related to farming, forestry, rural economic development, and food. It aims to meet the needs of com ...
Forest Service suggested that the rise in maize cultivation 500 to 1,000 years ago in what is now the southeastern United States corresponded with a decline of freshwater mussels, which are very sensitive to environmental changes.
Cultivation
Planting
Because it is cold-intolerant, in the
temperate zones
In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout t ...
maize must be planted in the spring. Its
root
In vascular plants, the roots are the organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants to grow taller and faster. They are most often below the su ...
system is generally shallow, so the plant is dependent on soil moisture. As a plant that uses C4 carbon fixation, maize is a considerably more water-efficient crop than plants that use
C3 carbon fixation
carbon fixation is the most common of three metabolic pathways for carbon fixation in photosynthesis, along with C4 carbon fixation, and Crassulacean acid metabolism, CAM. This process converts carbon dioxide and ribulose bisphosphate (RuBP, a ...
such as alfalfa and soybeans. Maize is most sensitive to drought at the time of silk emergence, when the flowers are ready for pollination. In the United States, a good harvest was traditionally predicted if the maize was "knee-high by the
Fourth of July
Independence Day (colloquially the Fourth of July) is a federal holiday in the United States commemorating the Declaration of Independence, which was ratified by the Second Continental Congress on July 4, 1776, establishing the United States ...
", although modern hybrids generally exceed this growth rate. Maize used for
silage
Silage () is a type of fodder made from green foliage crops which have been preserved by fermentation to the point of acidification. It can be fed to cattle, sheep and other such ruminants (cud-chewing animals). The fermentation and storage ...
is harvested while the plant is green and the fruit immature. Sweet corn is harvested in the "milk stage", after pollination but before starch has formed, between late summer and early to mid-autumn. Field maize is left in the field until very late in the autumn to thoroughly dry the grain, and may, in fact, sometimes not be harvested until winter or even early spring. The importance of sufficient soil moisture is shown in many parts of Africa, where periodic
drought
A drought is defined as drier than normal conditions.Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D. Jiang, A. Khan, W. Pokam Mba, D. Rosenfeld, J. Tierney, an ...
regularly causes maize crop failure and consequent
famine
A famine is a widespread scarcity of food, caused by several factors including war, natural disasters, crop failure, population imbalance, widespread poverty, an economic catastrophe or government policies. This phenomenon is usually accompani ...
. Although it is grown mainly in wet, hot climates, it has been said to thrive in cold, hot, dry or wet conditions, meaning that it is an extremely versatile crop.
Maize was planted by the Native Americans in hills, in a complex system known to some as the Three Sisters. Maize provided support for beans, and the beans provided nitrogen derived from nitrogen-fixing rhizobia bacteria which live on the roots of beans and other legumes; and squashes provided ground cover to stop weeds and inhibit evaporation by providing shade over the soil. This method was replaced by single species hill planting where each hill apart was planted with three or four seeds, a method still used by home gardeners. A later technique was "checked maize", where hills were placed apart in each direction, allowing cultivators to run through the field in two directions. In more arid lands, this was altered and seeds were planted in the bottom of deep furrows to collect water. Modern technique plants maize in rows which allows for cultivation while the plant is young, although the hill technique is still used in the maize fields of some Native American reservations. When maize is planted in rows, it also allows for planting of other crops between these rows to make more efficient use of land space.
In most regions today, maize grown in residential
garden
A garden is a planned space, usually outdoors, set aside for the cultivation, display, and enjoyment of plants and other forms of nature. The single feature identifying even the wildest wild garden is ''control''. The garden can incorporate bot ...
s is still often planted manually with a hoe, whereas maize grown commercially is no longer planted manually but rather is planted with a planter. In North America, fields are often planted in a two-
crop rotation
Crop rotation is the practice of growing a series of different types of crops in the same area across a sequence of growing seasons. It reduces reliance on one set of nutrients, pest and weed pressure, and the probability of developing resistant ...
with a
nitrogen-fixing
Nitrogen fixation is a chemical process by which molecular nitrogen (), with a strong triple covalent bond, in the air is converted into ammonia () or related nitrogenous compounds, typically in soil or aquatic systems but also in industry. Atm ...
soybean
The soybean, soy bean, or soya bean (''Glycine max'') is a species of legume native to East Asia, widely grown for its edible bean, which has numerous uses.
Traditional unfermented food uses of soybeans include soy milk, from which tofu a ...
s in regions with longer summers. Sometimes a third crop,
winter wheat
Winter wheat (usually '' Triticum aestivum'') are strains of wheat that are planted in the autumn to germinate and develop into young plants that remain in the vegetative phase during the winter and resume growth in early spring. Classificatio ...
, is added to the rotation.
Many of the maize varieties grown in the United States and Canada are hybrids. Often the varieties have been
genetically modified
Genetic engineering, also called genetic modification or genetic manipulation, is the modification and manipulation of an organism's genes using technology. It is a set of technologies used to change the genetic makeup of cells, including ...
to tolerate
glyphosate
Glyphosate (IUPAC name: ''N''-(phosphonomethyl)glycine) is a broad-spectrum systemic herbicide and crop desiccant. It is an organophosphorus compound, specifically a phosphonate, which acts by inhibiting the plant enzyme 5-enolpyruvylshik ...
or to provide protection against natural pests. Glyphosate is an herbicide which kills all plants except those with genetic tolerance. This genetic tolerance is very rarely found in nature.
In the midwestern United States, low-till or
no-till farming
No-till farming (also known as zero tillage or direct drilling) is an agricultural technique for growing crops or pasture without disturbing the soil through tillage. No-till farming decreases the amount of soil erosion tillage causes in certai ...
techniques are usually used. In low-till, fields are covered once, maybe twice, with a tillage implement either ahead of crop planting or after the previous harvest. The fields are planted and
fertilized
Fertilisation or fertilization (see spelling differences), also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes to give rise to a new individual organism or offspring and initiate its development. Proce ...
.
Weed
A weed is a plant considered undesirable in a particular situation, "a plant in the wrong place", or a plant growing where it is not wanted.Harlan, J. R., & deWet, J. M. (1965). Some thoughts about weeds. ''Economic botany'', ''19''(1), 16-24. ...
s are controlled through the use of herbicides, and no cultivation tillage is done during the growing season. This technique reduces moisture evaporation from the soil, and thus provides more moisture for the crop.
The technologies mentioned in the previous paragraph enable low-till and no-till farming. Weeds compete with the crop for moisture and nutrients, making them undesirable.
Harvesting
Maize harvested as a grain crop can be kept in the field a relatively long time, even months, after the crop is ready to harvest; it is also harvested and stored in the husk leaves if kept dry.
Before the 20th century, all maize harvesting was by
manual labour
Manual labour (in Commonwealth English, manual labor in American English) or manual work is physical work done by humans, in contrast to labour by machines and working animals. It is most literally work done with the hands (the word ''manual ...
, by
grazing
In agriculture, grazing is a method of animal husbandry whereby domestic livestock are allowed outdoors to roam around and consume wild vegetations in order to convert the otherwise indigestible (by human gut) cellulose within grass and other ...
, or by some combination of those. Whether the ears were hand-picked and the stover was grazed, or the whole plant was cut, gathered, and shocked, people and
livestock
Livestock are the domesticated animals raised in an agricultural setting to provide labor and produce diversified products for consumption such as meat, eggs, milk, fur, leather, and wool. The term is sometimes used to refer solely to animal ...
did all the work. Between the 1890s and the 1970s, the technology of maize harvesting expanded greatly. Today, all such technologies, from entirely manual harvesting to entirely mechanized, are still in use to some degree, as appropriate to each farm's needs, although the thoroughly mechanized versions predominate, as they offer the lowest
unit cost
The unit cost is the price incurred by a company
A company, abbreviated as co., is a legal entity representing an association of people, whether natural, legal or a mixture of both, with a specific objective. Company members share a com ...
s when scaled to large farm operations.
Before
World War II
World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposing ...
, most maize in North America was harvested by hand. This involved a large number of workers and associated social events (husking or shucking bees). From the 1890s onward, some machinery became available to partially mechanize the processes, such as one- and two-row mechanical pickers (picking the ear, leaving the stover) and corn binders, which are
reaper-binder
The reaper-binder, or binder, is a farm implement that improved upon the simple reaper. The binder was invented in 1872 by Charles Baxter Withington, a jeweler from Janesville, Wisconsin. In addition to cutting the small-grain crop, a binder also ...
s designed specifically for maize (for example, ). The latter produce sheaves that can be shocked. By hand or mechanical picker, the entire ear is harvested, which then requires a separate operation of a maize sheller to remove the kernels from the ear. Whole ears of maize were often stored in corn cribs, and these whole ears are a sufficient form for some livestock feeding use. Today corn cribs with whole ears, and corn binders, are less common because most modern farms harvest the grain from the field with a combine and store it in bins. The combine with a corn head (with points and snap rolls instead of a reel) does not cut the stalk; it simply pulls the stalk down. The stalk continues downward and is crumpled into a mangled pile on the ground, where it usually is left to become organic matter for the
soil
Soil, also commonly referred to as earth or dirt
Dirt is an unclean matter, especially when in contact with a person's clothes, skin, or possessions. In such cases, they are said to become dirty.
Common types of dirt include:
* Debri ...
. The ear of maize is too large to pass between slots in a plate as the snap rolls pull the stalk away, leaving only the ear and husk to enter the machinery. The combine separates the husk and the cob, keeping only the kernels.
The entire maize plant is also harvested as a
silage
Silage () is a type of fodder made from green foliage crops which have been preserved by fermentation to the point of acidification. It can be fed to cattle, sheep and other such ruminants (cud-chewing animals). The fermentation and storage ...
crop.
For storing grain in bins, the moisture of the grain must be sufficiently low to avoid spoiling. If the moisture content of the harvested grain is too high, grain dryers are used to reduce the moisture content by blowing heated air through the grain. This can require large amounts of energy in the form of combustible gases ( propane or
natural gas
Natural gas (also called fossil gas or simply gas) is a naturally occurring mixture of gaseous hydrocarbons consisting primarily of methane in addition to various smaller amounts of other higher alkanes. Low levels of trace gases like carbo ...
) and electricity to power the blowers.
Production
Maize is widely cultivated throughout the world, and a greater weight of maize is produced each year than any other grain. In 2020, total world production was 1.16 billion
tonne
The tonne ( or ; symbol: t) is a unit of mass equal to 1000 kilograms. It is a non-SI unit accepted for use with SI. It is also referred to as a metric ton to distinguish it from the non-metric units of the short ton ( United State ...
s, led by the United States with 31.0% of the total (table). China produced 22.4% of the global total.
United States
In 2016, maize production was forecast to be over 380 million metric tons (15 billion
bushel
A bushel (abbreviation: bsh. or bu.) is an imperial and US customary unit of volume based upon an earlier measure of dry capacity. The old bushel is equal to 2 kennings (obsolete), 4 pecks, or 8 dry gallons, and was used mostly for agric ...
s), an increase of 11% over 2014 American production. Based on conditions as of August 2016, the expected yield would be the highest ever for the United States. The area of harvested maize was forecast to be , an increase of 7% over 2015. Maize is especially popular in
Midwestern
The Midwestern United States, also referred to as the Midwest or the American Midwest, is one of four census regions of the United States Census Bureau (also known as "Region 2"). It occupies the northern central part of the United States. I ...
states such as
Indiana
Indiana () is a U.S. state in the Midwestern United States. It is the 38th-largest by area and the 17th-most populous of the 50 States. Its capital and largest city is Indianapolis. Indiana was admitted to the United States as the 19th s ...
,
Iowa
Iowa () is a state in the Midwestern region of the United States, bordered by the Mississippi River to the east and the Missouri River and Big Sioux River to the west. It is bordered by six states: Wisconsin to the northeast, Illinois to th ...
, and
Illinois
Illinois ( ) is a state in the Midwestern United States. Its largest metropolitan areas include the Chicago metropolitan area, and the Metro East section, of Greater St. Louis. Other smaller metropolitan areas include, Peoria and Rockf ...
; in the latter, it was named the state's official grain in 2017.
The estimated corn usage for crop year September 1, 2020 to August 31, 2021, was 38.7 percent was used for feed, 34 percent for ethanol, 17.5 percent for export, and 9.8 percent for food.
Trade
Corn futures are traded on several exchanges, the Chicago Board of Trade (CBOT) and JSE Derivatives (JDERIV). The Chicago Board Of Trade sells corn futures with a contact size of 5000 bushels which is quoted in cents/bushel and the JDERIV has a contact size of 100 Tonnes, quoted in Rand/Ton. The detailed contract specifications are listed below:
Diabrotica
''Diabrotica'' is a large, widespread genus of beetles in the family Chrysomelidae. Members of this genus include several destructive agricultural pest species, sometimes referred to as cucumber beetles or corn rootworms.
Species
* '' Diabrot ...
Euxesta stigmatias
''Euxesta stigmatias'' is a species of picture-winged fly in the genus '' Euxesta'' of the family Ulidiidae. The larva attacks maize
Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North A ...
'')
* Dusky
sap beetle
The sap beetles, also known as Nitidulidae, are a family of beetles.
They are small (2–6 mm) ovoid, usually dull-coloured beetles, with knobbed antennae. Some have red or yellow spots or bands. They feed mainly on decaying vegetable ma ...
European corn borer
The European corn borer (''Ostrinia nubilalis''), also known as the European corn worm or European high-flyer, is a moth of the family Crambidae which includes other grass moths. It is a pest of grain, particularly maize (''Zea mays''). The in ...
(''Ostrinia nubilalis'') (ECB)
* Fall armyworm (''Spodoptera frugiperda'') Some sweet corn varieties have developed partial resistance to fall army worms by producing a unique 33-kD proteinase that significantly retards fall army worm growth.
* Corn earworm/Cotton bollworm (''
Helicoverpa zea
''Helicoverpa zea, ''commonly known as the corn earworm, is a species (formerly in the genus ''Heliothis'') in the family Noctuidae. The larva of the moth ''Helicoverpa zea'' is a major agricultural pest. Since it is polyphagous (feeds on many ...
Maize weevil
Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. The ...
(''Sitophilus zeamais'')
* Northern armyworm, Oriental armyworm or Rice ear-cutting caterpillar ('' Mythimna separata'')
* Southwestern corn borer (''Diatraea grandiosella'')
* Stalk borer (''Papaipema nebris'')
The susceptibility of maize to the European corn borer and corn rootworms, and the resulting large crop losses which are estimated at a billion dollars worldwide for each pest, led to the development of transgenics expressing the '' Bacillus thuringiensis'' toxin. "Bt maize" is widely grown in the United States and has been approved for release in Europe.
Diseases
*
Rust
Rust is an iron oxide, a usually reddish-brown oxide formed by the reaction of iron and oxygen in the catalytic presence of water or air moisture. Rust consists of hydrous iron(III) oxides (Fe2O3·nH2O) and iron(III) oxide-hydroxide (FeO( ...
*
Corn smut
Corn smut is a plant disease caused by the pathogenic fungus ''Ustilago maydis'' that causes smut on maize and teosinte. The fungus forms galls on all above-ground parts of corn species. It is edible, and is known in Mexico as the delicacy ''h ...
or common smut (''Ustilago maydis''): a fungal disease, known in Mexico as ''huitlacoche'', which is prized by some as a gourmet delicacy in itself
* Northern corn leaf bligh (Purdue Extension site)(Pioneer site)
*
Southern corn leaf blight
Southern corn leaf blight (SCLB) is a fungal disease of maize caused by the plant pathogen '' Bipolaris maydis'' (also known as '' Cochliobolus heterostrophus'' in its
teleomorph state).
The fungus is an Ascomycete and can use conidia or asco ...
Maize dwarf mosaic virus
''Maize dwarf mosaic virus'' (MDMV) is a pathogenic plant virus of the family ''Potyviridae''. Depending on the corn plant’s growth stage, the virus can have severe implications to the corn plant’s development which can also result in economi ...
*
Maize streak virus
''Maize streak virus'' (MSV) is a virus primarily known for causing maize streak disease (MSD) in its major host, and which also infects over 80 wild and domesticated grasses. It is an insect-transmitted maize pathogen in the genus ''Mastrevirus ...
Aspergillus flavus
''Aspergillus flavus'' is a saprotrophic and pathogenic fungus with a cosmopolitan distribution. It is best known for its colonization of cereal grains, legumes, and tree nuts. Postharvest rot typically develops during harvest, storage, and/or ...
mycotoxin
A mycotoxin (from the Greek μύκης , "fungus" and τοξίνη , "toxin") is a toxic secondary metabolite produced by organisms of kingdom Fungi and is capable of causing disease and death in both humans and other animals. The term 'mycotoxin' ...
contamination. ''
Aspergillus
' () is a genus consisting of several hundred mold species found in various climates worldwide.
''Aspergillus'' was first catalogued in 1729 by the Italian priest and biologist Pier Antonio Micheli. Viewing the fungi under a microscope, Mic ...
'' and ''
Fusarium
''Fusarium'' is a large genus of filamentous fungi, part of a group often referred to as hyphomycetes, widely distributed in soil and associated with plants. Most species are harmless saprobes, and are relatively abundant members of the soil mi ...
'' spp. are the most common mycotoxin sources, but there are others. Altogether maize contaminants are so common, and this crop is so economically important, that maize mycotoxins are among the most important in agriculture in general.
Uses
Human food
Maize and cornmeal (ground dried maize) constitute a staple food in many regions of the world. Maize is used to produce
cornstarch
Corn starch, maize starch, or cornflour (British English) is the starch derived from corn (maize) grain. The starch is obtained from the endosperm of the kernel. Corn starch is a common food ingredient, often used to thicken sauces or so ...
, a common ingredient in home cooking and many industrialized food products. Maize starch can be hydrolyzed and enzymatically treated to produce syrups, particularly
high fructose corn syrup
High-fructose corn syrup (HFCS), also known as glucose–fructose, isoglucose and glucose–fructose syrup, is a sweetener made from corn starch. As in the production of conventional corn syrup, the starch is broken down into glucose by enzy ...
, a sweetener; and also fermented and distilled to produce
grain alcohol
Ethanol (abbr. EtOH; also called ethyl alcohol, grain alcohol, drinking alcohol, or simply alcohol) is an organic compound. It is an alcohol with the chemical formula . Its formula can be also written as or (an ethyl group linked to a hyd ...
. Grain alcohol from maize is traditionally the source of Bourbon whiskey.
Corn flour
Cornflour may refer to:
* Cornflour (in the UK), corn starch, from the endosperm of the kernel of the corn (maize) grain
* Corn flour (in the US and elsewhere), very finely ground cornmeal, ground from dried maize
See also
* Flour
* Starch ...
is used to make cornbread and other baked products.
In prehistoric times
Mesoamerica
Mesoamerica is a historical region and cultural area in southern North America and most of Central America. It extends from approximately central Mexico through Belize, Guatemala, El Salvador, Honduras, Nicaragua, and northern Costa Rica ...
n women used a ''
metate
A metate (or mealing stone) is a type or variety of quern, a ground stone tool used for processing grain and seeds. In traditional Mesoamerican cultures, metates are typically used by women who would grind nixtamalized maize and other organic ...
'' to process maize into ground cornmeal, allowing the preparation of foods that were more calorie dense than popcorn. After ceramic vessels were invented the
Olmec
The Olmecs () were the earliest known major Mesoamerican civilization. Following a progressive development in Soconusco, they occupied the tropical lowlands of the modern-day Mexican states of Veracruz and Tabasco. It has been speculated that ...
people began to cook maize together with beans, improving the nutritional value of the staple meal. Although maize naturally contains
niacin
Niacin, also known as nicotinic acid, is an organic compound and a form of vitamin B3, an essential human nutrient. It can be manufactured by plants and animals from the amino acid tryptophan. Niacin is obtained in the diet from a variet ...
, an important nutrient, it was not
bioavailable
In pharmacology, bioavailability is a subcategory of absorption and is the fraction (%) of an administered drug that reaches the systemic circulation.
By definition, when a medication is administered intravenously, its bioavailability is 100%. Ho ...
without the process of
nixtamalization
Nixtamalization () is a process for the preparation of corn, or other grain, in which the grain is soaked and cooked in an alkaline solution, usually limewater (but sometimes aqueous alkali metal carbonates), washed, and then hulled. The ter ...
. The
Maya
Maya may refer to:
Civilizations
* Maya peoples, of southern Mexico and northern Central America
** Maya civilization, the historical civilization of the Maya peoples
** Maya language, the languages of the Maya peoples
* Maya (Ethiopia), a popul ...
used nixtamal meal to make varieties of porridges and tamales. The process was later used in the cuisine of the American South to prepare corn for
grits
Grits are a type of porridge made from boiled cornmeal. Hominy grits are a type of grits made from hominy – corn that has been treated with an alkali in a process called nixtamalization, with the pericarp (ovary wall) removed. Grits are of ...
Masa
''Masa'' (or ''masa de maíz'') (; ) is a maize dough that comes from ground nixtamalized corn. It is used for making corn tortillas, '' gorditas'', ''tamales'', '' pupusas'', and many other Latin American dishes. It is dried and powdered into ...
(cornmeal treated with limewater) is the main ingredient for
tortilla
A tortilla (, ) is a thin, circular unleavened flatbread originally made from maize hominy meal, and now also from wheat flour. The Aztecs and other Nahuatl speakers called tortillas ''tlaxcalli'' (). First made by the indigenous peoples of M ...
s,
atole
''Atole'' (, from Nahuatl '' ātōlli'' ), also known as ''atolli'' and ''atol de elote'', is a traditional hot corn- and masa-based beverage of Mexican origin. Chocolate ''atole'' is known as ''champurrado'' or ''atole''. It typically accom ...
and many other dishes of Central American food. It is the main ingredient of corn tortilla,
tamale
A tamale, in Spanish tamal, is a traditional Mesoamerican dish made of masa, a dough made from nixtamalized corn, which is steamed in a corn husk or banana leaf. The wrapping can either be discarded prior to eating or used as a plate. Tam ...
s,
pozole
Pozole (; from nah, pozoll, meaning ''cacahuazintle'', a variety of corn or maize) is a traditional soup or stew from Mexican cuisine. It is made from hominy with meat (typically pork, but possibly chicken), and can be seasoned and garnished w ...
,
atole
''Atole'' (, from Nahuatl '' ātōlli'' ), also known as ''atolli'' and ''atol de elote'', is a traditional hot corn- and masa-based beverage of Mexican origin. Chocolate ''atole'' is known as ''champurrado'' or ''atole''. It typically accom ...
and all the dishes based on them, like
taco
A taco (, , ) is a traditional Mexican food consisting of a small hand-sized corn- or wheat-based tortilla topped with a filling. The tortilla is then folded around the filling and eaten by hand. A taco can be made with a variety of fillin ...
s,
quesadilla
A quesadilla (; ; Mexican diminutive of ''quesada'') is a Mexican dish consisting of a tortilla that is filled primarily with cheese, and sometimes meats, spices, and other fillings, and then cooked on a griddle or stove. Traditionally, a co ...
s,
chilaquiles
Chilaquiles () are a traditional Mexican breakfast dish consisting of corn tortillas cut into quarters and lightly fried.
Ingredients and variations
Typically, corn tortillas cut into quarters and lightly fried or baked for a lighter version ...
,
enchilada
An enchilada (, ) is a Mexican dish consisting of a corn tortilla rolled around a filling and covered with a savory sauce. Enchiladas can be filled with various ingredients, including meats, cheese, beans, potatoes, vegetables, or combinations. ...
s, tostadas and many more. In Mexico the fungus of maize, known as
huitlacoche
Corn smut is a plant disease caused by the pathogenic fungus ''Ustilago maydis'' that causes smut on maize and teosinte. The fungus forms galls on all above-ground parts of corn species. It is edible, and is known in Mexico as the delicacy ''h ...
, is considered a delicacy.
Coarse maize meal is made into a thick porridge in many cultures: from the polenta of Italy, the ''angu'' of Brazil, the ''
mămăligă
Mămăligă (;) is a porridge made out of yellow maize flour, traditional in Romania, Moldova and West Ukraine. Poles from the Lviv area also prepare this traditional dish. It is also a traditional dish in Thessaly and Fthiotis, Greece. In Ita ...
'' of Romania, to
cornmeal mush
Mush is a type of cornmeal pudding (or porridge) which is usually boiled in water or milk. It is often allowed to set, or gel into a semisolid, then cut into flat squares or rectangles, and pan fried. Usage is especially common in the Eastern U ...
grits
Grits are a type of porridge made from boiled cornmeal. Hominy grits are a type of grits made from hominy – corn that has been treated with an alkali in a process called nixtamalization, with the pericarp (ovary wall) removed. Grits are of ...
in the South) or the food called mieliepap in South Africa and sadza, nshima, ugali and other names in other parts of Africa. Introduced into Africa by the Portuguese in the 16th century, maize has become Africa's most important staple food crop. These are commonly eaten in the
Southeastern United States
The Southeastern United States, also referred to as the American Southeast or simply the Southeast, is a geographical region of the United States. It is located broadly on the eastern portion of the southern United States and the southern por ...
, foods handed down from Native Americans, who called the dish sagamite.
Maize can also be harvested and consumed in the unripe state, when the kernels are fully grown but still soft. Unripe maize must usually be cooked to become palatable; this may be done by simply boiling or roasting the whole ears and eating the kernels right off the cob. Sweet corn, a genetic variety that is high in sugars and low in starch, is usually consumed in the unripe state. Such corn on the cob is a common dish in the United States, Canada, United Kingdom, Cyprus, some parts of South America, and the Balkans, but virtually unheard of in some European countries. Corn on the cob was hawked on the streets of early 19th-century New York City by poor, barefoot " Hot Corn Girls", who were thus the precursors of
hot dog cart
A hot dog cart is a specialized mobile food stand for preparing and selling street food
Street food is ready-to-eat food or drinks sold by a hawker, or vendor, in a street or at other public places, such as markets or fairs. It is often sold ...
s,
churro
A churro (, ) is a type of fried dough from Spanish and Portuguese cuisine. They are also found in Latin American cuisine and in other areas that have received immigration from Spanish and Portuguese-speaking countries, especially in the Sou ...
wagons, and fruit stands seen on the streets of big cities today.
Within the United States, the usage of maize for human consumption constitutes only around 1/40th of the amount grown in the country. In the United States and Canada, maize is mostly grown to feed
livestock
Livestock are the domesticated animals raised in an agricultural setting to provide labor and produce diversified products for consumption such as meat, eggs, milk, fur, leather, and wool. The term is sometimes used to refer solely to animal ...
, as forage,
silage
Silage () is a type of fodder made from green foliage crops which have been preserved by fermentation to the point of acidification. It can be fed to cattle, sheep and other such ruminants (cud-chewing animals). The fermentation and storage ...
(made by fermentation of chopped green cornstalks), or grain. Maize meal is also a significant ingredient of some commercial animal food products.
Nutritional value
Raw, yellow, sweet maize kernels are composed of 76% water, 19% carbohydrates, 3%
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...
, and 1%
fat
In nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such compounds, most commonly those that occur in living beings or in food.
The term often refers specifically to triglycerides (triple est ...
(table). In a 100-
gram
The gram (originally gramme; SI unit symbol g) is a unit of mass in the International System of Units (SI) equal to one one thousandth of a kilogram.
Originally defined as of 1795 as "the absolute weight of a volume of pure water equal to th ...
serving, maize kernels provide 86
calories
The calorie is a unit of energy. For historical reasons, two main definitions of "calorie" are in wide use. The large calorie, food calorie, or kilogram calorie was originally defined as the amount of heat needed to raise the temperature of o ...
and are a good source (10–19% of the
Daily Value
The Reference Daily Intake (RDI) used in nutrition labeling on food and dietary supplement products in the U.S. and Canada is the daily intake level of a nutrient that is considered to be sufficient to meet the requirements of 97–98% of healthy ...
) of the
B vitamins
B vitamins are a class of water-soluble vitamins that play important roles in cell metabolism and synthesis of red blood cells. Though these vitamins share similar names (B1, B2, B3, etc.), they are chemically distinct compounds that often coexi ...
,
thiamin
Thiamine, also known as thiamin and vitamin B1, is a vitamin, an essential micronutrient, that cannot be made in the body. It is found in food and commercially synthesized to be a dietary supplement or medication. Phosphorylated forms of t ...
,
niacin
Niacin, also known as nicotinic acid, is an organic compound and a form of vitamin B3, an essential human nutrient. It can be manufactured by plants and animals from the amino acid tryptophan. Niacin is obtained in the diet from a variet ...
pantothenic acid
Pantothenic acid, also called vitamin B5 is a water-soluble B vitamin and therefore an essential nutrient. All animals require pantothenic acid in order to synthesize coenzyme A (CoA) – essential for fatty acid metabolism – as well as to, ...
(B5) and
folate
Folate, also known as vitamin B9 and folacin, is one of the B vitamins. Manufactured folic acid, which is converted into folate by the body, is used as a dietary supplement and in food fortification as it is more stable during processing an ...
(right table for raw, uncooked kernels,
USDA
The United States Department of Agriculture (USDA) is the federal executive department responsible for developing and executing federal laws related to farming, forestry, rural economic development, and food. It aims to meet the needs of com ...
magnesium
Magnesium is a chemical element with the symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 of the periodic ta ...
and
phosphorus
Phosphorus is a chemical element with the symbol P and atomic number 15. Elemental phosphorus exists in two major forms, white phosphorus and red phosphorus, but because it is highly reactive, phosphorus is never found as a free element on Ear ...
whereas other nutrients are in low amounts (table).
Maize has suboptimal amounts of the
essential amino acid
An essential amino acid, or indispensable amino acid, is an amino acid that cannot be synthesized from scratch by the organism fast enough to supply its demand, and must therefore come from the diet. Of the 21 amino acids common to all life form ...
s
tryptophan
Tryptophan (symbol Trp or W)
is an α-amino acid that is used in the biosynthesis of proteins. Tryptophan contains an α-amino group, an α-carboxylic acid group, and a side chain indole, making it a polar molecule with a non-polar aromatic ...
and lysine, which accounts for its lower status as a protein source. However, the proteins of beans and legumes complement those of maize.
Feed and fodder for livestock
Maize is a major source of both grain feed and fodder for
livestock
Livestock are the domesticated animals raised in an agricultural setting to provide labor and produce diversified products for consumption such as meat, eggs, milk, fur, leather, and wool. The term is sometimes used to refer solely to animal ...
. It is fed to the livestock in various ways. When it is used as a grain crop, the dried
kernels
Kernel may refer to:
Computing
* Kernel (operating system), the central component of most operating systems
* Kernel (image processing), a matrix used for image convolution
* Compute kernel, in GPGPU programming
* Kernel method, in machine learnin ...
are used as feed. They are often kept on the cob for storage in a corn crib, or they may be shelled off for storage in a
grain bin
A silo (from the Greek σιρός – ''siros'', "pit for holding grain") is a structure for storing bulk materials. Silos are used in agriculture to store fermented feed known as silage, not to be confused with a grain bin, which is use ...
. The farm that consumes the feed may produce it, purchase it on the market, or some of both. When the grain is used for feed, the rest of the plant (the corn stover) can be used later as fodder,
bedding
Bedding, also known as bedclothes or bed linen, is the materials laid above the mattress of a bed for hygiene, warmth, protection of the mattress, and decorative effect. Bedding is the removable and washable portion of a human sleeping environm ...
(litter), or soil amendment. When the whole maize plant (grain plus stalks and leaves) is used for fodder, it is usually chopped all at once and ensilaged, as digestibility and palatability are higher in the ensilaged form than in the dried form. Maize silage is one of the most valuable forages for ruminants. Before the advent of widespread ensilaging, it was traditional to gather the corn into shocks after harvesting, where it dried further. With or without a subsequent move to the cover of a barn, it was then stored for weeks to several months until fed to the livestock. Today ensilaging can occur not only in siloes but also in silage wrappers. However, in the tropics, maize can be harvested year-round and fed as green forage to the animals.
fabric
Textile is an umbrella term that includes various fiber-based materials, including fibers, yarns, filaments, threads, different fabric types, etc. At first, the word "textiles" only referred to woven fabrics. However, weaving is not th ...
s, adhesives, and many other chemical products.
The
corn steep liquor Corn steep liquor is a by-product of corn wet-milling. A viscous concentrate of corn solubles which contains amino acids, vitamins and minerals, it is an important constituent of some growth media. It was used in the culturing of ''Penicillium'' du ...
, a plentiful watery byproduct of maize
wet milling Wet-milling is a process in which feed material is steeped in water, with or without sulfur dioxide, to soften the seed kernel in order to help separate the kernel’s various components. For example, wet-milling plants can separate a 56-pound bu ...
process, is widely used in the biochemical industry and research as a culture medium to grow many kinds of
microorganism
A microorganism, or microbe,, ''mikros'', "small") and ''organism'' from the el, ὀργανισμός, ''organismós'', "organism"). It is usually written as a single word but is sometimes hyphenated (''micro-organism''), especially in olde ...
s.
Chrysanthemin
Chrysanthemin is an anthocyanin. It is the 3-glucoside of cyanidin.
Natural occurrences
Chrysanthemin can be found in the roselle plant (''Hibiscus sabdariffa'', Malvaceae), different Japanese angiosperms, '' Rhaponticum'' (Asteraceae), The fr ...
is found in purple corn and is used as a food coloring.
Bio-fuel
"Feed maize" is being used increasingly for heating; specialized corn stoves (similar to wood stoves) are available and use either feed maize or wood pellets to generate heat. Maize cobs are also used as a biomass fuel source. Maize is relatively cheap and home-heating furnaces have been developed which use maize kernels as a fuel. They feature a large hopper that feeds the uniformly sized maize kernels (or wood pellets or cherry pits) into the fire.
Maize is increasingly used as a feedstock for the production of
ethanol fuel
Ethanol fuel is ethyl alcohol, the same type of alcohol found in alcoholic beverages, used as fuel. It is most often used as a motor fuel, mainly as a biofuel additive for gasoline. The first production car running entirely on ethanol was t ...
. When considering where to construct an ethanol plant, one of the site selection criteria is to ensure there is locally available feedstock. Ethanol is mixed with gasoline to decrease the amount of pollutants emitted when used to fuel motor vehicles. High fuel prices in mid-2007 led to higher demand for ethanol, which in turn led to higher prices paid to farmers for maize. This led to the 2007 harvest being one of the most profitable maize crops in modern history for farmers. Because of the relationship between fuel and maize, prices paid for the crop now tend to track the price of oil.
The price of food is affected to a certain degree by the use of maize for biofuel production. The cost of transportation, production, and marketing are a large portion (80%) of the price of food in the United States. Higher energy costs affect these costs, especially transportation. The increase in
food prices
Food prices refer to the average price level for food across countries, regions and on a global scale. Food prices have an impact on producers and consumers of food.
Price levels depend on the food production process, including food marketing ...
the consumer has been seeing is mainly due to the higher energy cost. The effect of biofuel production on other food crop prices is indirect. Use of maize for biofuel production increases the demand, and therefore price of maize. This, in turn, results in farm acreage being diverted from other food crops to maize production. This reduces the supply of the other food crops and increases their prices.
Maize is widely used in Germany as a feedstock for
biogas plants
Anaerobic digestion is a sequence of processes by which microorganisms break down biodegradable material in the absence of oxygen. The process is used for industrial or domestic purposes to manage waste or to produce fuels. Much of the ferment ...
. Here the maize is harvested, shredded then placed in
silage
Silage () is a type of fodder made from green foliage crops which have been preserved by fermentation to the point of acidification. It can be fed to cattle, sheep and other such ruminants (cud-chewing animals). The fermentation and storage ...
clamps from which it is fed into the biogas plants. This process makes use of the whole plant rather than simply using the kernels as in the production of fuel ethanol.
A biomass gasification power plant in Strem near
Güssing
Güssing (; hu, Németújvár, Német-Újvár, hr, Novi Grad) is a town in Burgenland, Austria. It is located at , with a population of 3,578 (2022), and is the administrative center of the Güssing district. For centuries the town occupied an i ...
,
Burgenland
Burgenland (; hu, Őrvidék; hr, Gradišće; Austro-Bavarian: ''Burgnland;'' Slovene: ''Gradiščanska'') is the easternmost and least populous state of Austria. It consists of two statutory cities and seven rural districts, with a total of ...
, Austria, began in 2005. There is potential that
diesel
Diesel may refer to:
* Diesel engine, an internal combustion engine where ignition is caused by compression
* Diesel fuel, a liquid fuel used in diesel engines
* Diesel locomotive, a railway locomotive in which the prime mover is a diesel engin ...
can be created from the biogas by the Fischer Tropsch method.
Increasingly, ethanol is being used at low concentrations (10% or less) as an additive in
gasoline
Gasoline (; ) or petrol (; ) (see ) is a transparent, petroleum-derived flammable liquid that is used primarily as a fuel in most spark-ignited internal combustion engines (also known as petrol engines). It consists mostly of organi ...
( gasohol) for motor fuels to increase the octane rating, lower pollutants, and reduce petroleum use (what is nowadays also known as " biofuels" and has been generating an intense debate regarding the human beings' necessity of new sources of energy, on the one hand, and the need to maintain, in regions such as Latin America, the food habits and culture which has been the essence of civilizations such as the one originated in Mesoamerica; the entry, January 2008, of maize among the commercial agreements of NAFTA has increased this debate, considering the bad labor conditions of workers in the fields, and mainly the fact that NAFTA "opened the doors to the import of maize from the United States, where the farmers who grow it receive multimillion-dollar subsidies and other government supports. ... According to OXFAM UK, after NAFTA went into effect, the price of maize in Mexico fell 70% between 1994 and 2001. The number of farm jobs dropped as well: from 8.1 million in 1993 to 6.8 million in 2002. Many of those who found themselves without work were small-scale maize growers."). However, introduction in the northern latitudes of the US o tropical maize for biofuels and not for human or animal consumption, may potentially alleviate this.
Commodity
Maize is bought and sold by investors and price speculators as a tradable commodity using corn
futures contract
In finance, a futures contract (sometimes called a futures) is a standardized legal contract to buy or sell something at a predetermined price for delivery at a specified time in the future, between parties not yet known to each other. The asset ...
ticker symbol
A ticker symbol or stock symbol is an abbreviation used to uniquely identify publicly traded shares of a particular stock on a particular stock market. In short, ticker symbols are arrangements of symbols or characters (generally Latin letters ...
C. They are delivered every year in March, May, July, September, and December.
Ornamental and other uses
Some forms of the plant are occasionally grown for ornamental use in the garden. For this purpose, variegated and colored leaf forms as well as those with colorful ears are used.
Corncobs can be hollowed out and treated to make inexpensive
smoking pipes
A tobacco pipe, often called simply a pipe, is a device specifically made to smoke tobacco. It comprises a chamber (the bowl) for the tobacco from which a thin hollow stem (shank) emerges, ending in a mouthpiece. Pipes can range from very simp ...
, first manufactured in the United States in 1869.
An unusual use for maize is to create a "
corn maze
A corn maze or maize maze is a maze cut out of a corn field. Originally, the first full-size corn maze was believed to be created in Annville, Pennsylvania in 1993; however, similar corn mazes were highlighted in newspapers as early as 1982. C ...
" (or "maize maze") as a tourist attraction. The idea of a maize maze was introduced by the American Maze Company who created a maze in
Pennsylvania
Pennsylvania (; ( Pennsylvania Dutch: )), officially the Commonwealth of Pennsylvania, is a state spanning the Mid-Atlantic, Northeastern, Appalachian, and Great Lakes regions of the United States. It borders Delaware to its southeast, ...
in 1993. Traditional mazes are most commonly grown using yewhedges, but these take several years to mature. The rapid growth of a field of maize allows a maze to be laid out using
GPS
The Global Positioning System (GPS), originally Navstar GPS, is a satellite-based radionavigation system owned by the United States government and operated by the United States Space Force. It is one of the global navigation satellite sy ...
at the start of a growing season and for the maize to grow tall enough to obstruct a visitor's line of sight by the start of the summer. In Canada and the US, these are popular in many farming communities.
Maize kernels can be used in place of sand in a sandboxlike enclosure for children's play.
Stigmas from female maize flowers, popularly called
corn silk
Corn silk is a common ''Stigma maydis'', the shiny, thread-like, weak fibers that grow as part of ears of corn (maize); the tuft or tassel of silky fibers that protrude from the tip of the ear of corn. The ear is enclosed in modified leaves called ...
, are sold as
herbal supplements
Herbal medicine (also herbalism) is the study of pharmacognosy and the use of medicinal plants, which are a basis of traditional medicine. With worldwide research into pharmacology, some herbal medicines have been translated into modern remedies ...
.
Maize is used as a
fish bait
Fishing bait is any substance used to attract and catch fish, e.g. on a fishing hook. Bait items are both selected from and placed within the environment to achieve enhanced prey capture success. Traditionally, fishing baits are natural fish foo ...
, called "dough balls". It is particularly popular in Europe for
coarse fishing
In Britain and Ireland, coarse fishing (, ) refers to angling for rough fish, which are fish species traditionally considered undesirable as a food or game fish. Freshwater game fish are all salmonids — most particularly salmon, trout and ch ...
.
Additionally, feed corn is sometimes used by hunters to bait animals such as deer or wild hogs.
United States usage breakdown
The breakdown of usage of the 12.1-billion-
bushel
A bushel (abbreviation: bsh. or bu.) is an imperial and US customary unit of volume based upon an earlier measure of dry capacity. The old bushel is equal to 2 kennings (obsolete), 4 pecks, or 8 dry gallons, and was used mostly for agric ...
(307-million-tonne) 2008 US maize crop was as follows, according to the World Agricultural Supply and Demand Estimates Report by the USDA.
In the US since 2009/2010, maize feedstock use for ethanol production has somewhat exceeded direct use for livestock feed; maize use for fuel ethanol was 5,130 million bushels (130 million tonnes) in the 2013/2014 marketing year.
A fraction of the maize feedstock dry matter used for ethanol production is usefully recovered as DDGS (dried distillers grains with solubles). In the 2010/2011 marketing year, about 29.1 million tonnes of DDGS were fed to US livestock and poultry.Hoffman, L. and A. Baker. 2011. Estimating the substitution of distillers'grains for corn and soybean meal in the U.S. feed complex. United States Department of Agriculture, Economic Research Service. FDS-11-l-01. 62 pp. Because starch utilization in fermentation for ethanol production leaves other grain constituents more concentrated in the residue, the feed value per kg of DDGS, with regard to ruminant-metabolizable energy and protein, exceeds that of the grain. Feed value for monogastric animals, such as swine and poultry, is somewhat lower than for ruminants.
Comparison to other staple foods
The following table shows the nutrient content of maize and major staple foods in a raw harvested form on a dry weight basis to account for their different water contents. Raw forms are not edible and cannot be digested. These must be sprouted, or prepared and cooked for human consumption. In sprouted or cooked form, the relative nutritional and anti-nutritional contents of each of these staples are different from that of raw form of these staples reported in the table below.
Hazards
Pellagra
When maize was first introduced into farming systems other than those used by traditional native-American peoples, it was generally welcomed with enthusiasm for its productivity. However, a widespread problem of malnutrition soon arose wherever maize was introduced as a staple food. This was a mystery, since these types of malnutrition were not normally seen among the indigenous Americans, for whom maize was the principal staple food.
It was eventually discovered that the indigenous Americans had learned to soak maize in alkali — water (the process now known as
nixtamalization
Nixtamalization () is a process for the preparation of corn, or other grain, in which the grain is soaked and cooked in an alkaline solution, usually limewater (but sometimes aqueous alkali metal carbonates), washed, and then hulled. The ter ...
) — made with ashes and lime (
calcium oxide
Calcium oxide (CaO), commonly known as quicklime or burnt lime, is a widely used chemical compound. It is a white, caustic, alkaline, crystalline solid at room temperature. The broadly used term "''lime''" connotes calcium-containing inorganic ...
) since at least 1200–1500 BC by Mesoamericans. They did this to liberate the corn hulls, but (unbeknownst to natives or colonists) it coincidentally liberates the B-vitamin
niacin
Niacin, also known as nicotinic acid, is an organic compound and a form of vitamin B3, an essential human nutrient. It can be manufactured by plants and animals from the amino acid tryptophan. Niacin is obtained in the diet from a variet ...
, the lack of which was the underlying cause of the condition known as
pellagra
Pellagra is a disease caused by a lack of the vitamin niacin (vitamin B3). Symptoms include inflamed skin, diarrhea, dementia, and sores in the mouth. Areas of the skin exposed to either sunlight or friction are typically affected first. Over t ...
.
Maize was introduced into the diet of non-indigenous Americans without the necessary cultural knowledge acquired over thousands of years in the Americas. In the late 19th century, pellagra reached epidemic proportions in parts of the southern US, as medical researchers debated two theories for its origin: the deficiency theory (which was eventually shown to be true) said that pellagra was due to a deficiency of some nutrient, and the germ theory said that pellagra was caused by a germ transmitted by stable flies. A third theory, promoted by the eugenicist
Charles Davenport
Charles Benedict Davenport (June 1, 1866 – February 18, 1944) was a biologist and eugenicist influential in the American eugenics movement.
Early life and education
Davenport was born in Stamford, Connecticut, to Amzi Benedict Davenport, a ...
, held that people only contracted pellagra if they were susceptible to it due to certain "constitutional, inheritable" traits of the affected individual.Precis by Jan Coe /ref>
Once alkali processing and dietary variety were understood and applied, pellagra disappeared in the developed world. The development of high lysine maize and the promotion of a more balanced diet have also contributed to its demise. Pellagra still exists today in food-poor areas and refugee camps where people survive on donated maize. Also .
Allergy
Maize contains
lipid transfer protein
Plant lipid transfer proteins, also known as plant LTPs or PLTPs, are a group of highly- conserved proteins of about 7-9kDa found in higher plant tissues. As its name implies, lipid transfer proteins facilitate the shuttling of phospholipids and o ...
, an indigestible protein that survives cooking. This protein has been linked to a rare and understudied
allergy
Allergies, also known as allergic diseases, refer a number of conditions caused by the hypersensitivity of the immune system to typically harmless substances in the environment. These diseases include hay fever, food allergies, atopic derm ...
to maize in humans. The allergic reaction can cause skin rash, swelling or itching of
mucous membranes
A mucous membrane or mucosa is a membrane that lines various cavities in the body of an organism and covers the surface of internal organs. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue. It is ...
, diarrhea, vomiting,
asthma
Asthma is a long-term inflammatory disease of the airways of the lungs. It is characterized by variable and recurring symptoms, reversible airflow obstruction, and easily triggered bronchospasms. Symptoms include episodes of wheezing, co ...
and, in severe cases,
anaphylaxis
Anaphylaxis is a serious, potentially fatal allergic reaction and medical emergency that is rapid in onset and requires immediate medical attention regardless of use of emergency medication on site. It typically causes more than one of the foll ...
. It is unclear how common this allergy is in the general population.
The ''Z. mays'' plant has an OPALS allergy scale rating of 5 out of 10, indicating moderate potential to cause allergic reactions, exacerbated by over-use of the same plant throughout a garden. Corn pollen is heavy, large, and usually airborne in the early morning.
Mycotoxins
Fungicide application does not reduce fungal growth or mycotoxin dramatically, although it can be a part of a successful reduction strategy. Among the most common toxins are those produced by ''
Aspergillus
' () is a genus consisting of several hundred mold species found in various climates worldwide.
''Aspergillus'' was first catalogued in 1729 by the Italian priest and biologist Pier Antonio Micheli. Viewing the fungi under a microscope, Mic ...
'' and ''
Fusarium
''Fusarium'' is a large genus of filamentous fungi, part of a group often referred to as hyphomycetes, widely distributed in soil and associated with plants. Most species are harmless saprobes, and are relatively abundant members of the soil mi ...
'' spp. The most common toxins are
aflatoxin
Aflatoxins are various poisonous carcinogens and mutagens that are produced by certain molds, particularly ''Aspergillus'' species. The fungi grow in soil, decaying vegetation and various staple foodstuffs and commodities such as hay, sweetcorn ...
s,
fumonisin The fumonisins are a group of mycotoxins derived from ''Fusarium'' and their Liseola section. They have strong structural similarity to sphinganine, the backbone precursor of sphingolipids.
More specifically, it can refer to:
* Fumonisin B1
* Fum ...
s,
zearalenone
Zearalenone (ZEN), also known as RAL and F-2 mycotoxin, is a potent estrogenic metabolite produced by some ''Fusarium'' and ''Gibberella'' species. Specifically, the ''Gibberella zeae ,'' the fungal species where zearalenone was initially detected, ...
, and
ochratoxin A
Ochratoxin A—a toxin produced by different ''Aspergillus'' and ''Penicillium'' species — is one of the most-abundant food-contaminating mycotoxins. It is also a frequent contaminant of water-damaged houses and of heating ducts. Human exposure ...
.
Bt maize
Genetically modified maize (corn) is a genetically modified crop. Specific maize strains have been genetically engineered to express agriculturally-desirable traits, including resistance to pests and to herbicides. Maize strains with both trait ...
discourages insect vectors and by so doing it dramatically reduces concentrations of fumonisins, significantly reduces aflatoxins, but only mildly reduces others.
Art
Maize has been an essential crop in the
Andes
The Andes, Andes Mountains or Andean Mountains (; ) are the longest continental mountain range in the world, forming a continuous highland along the western edge of South America. The range is long, wide (widest between 18°S – 20°S ...
since the
pre-Columbian era
In the history of the Americas, the pre-Columbian era spans from the original settlement of North and South America in the Upper Paleolithic period through European colonization, which began with Christopher Columbus's voyage of 1492. Usually, ...
. The Moche culture from Northern Peru made ceramics from earth, water, and fire. This pottery was a sacred substance, formed in significant shapes and used to represent important themes. Maize was represented anthropomorphically as well as naturally.
In the United States, maize ears along with tobacco leaves are carved into the capitals of columns in the
United States Capitol
The United States Capitol, often called The Capitol or the Capitol Building, is the seat of the legislative branch of the United States federal government, which is formally known as the United States Congress. It is located on Capitol Hill ...
building. Maize itself is sometimes used for temporary architectural detailing when the intent is to celebrate the fall season, local agricultural productivity and culture. Bundles of dried maize stalks are often displayed along with pumpkins, gourds and straw in autumnal displays outside homes and businesses. A well-known example of architectural use is the
Corn Palace
The Corn Palace, commonly advertised as The World's Only Corn Palace and the Mitchell Corn Palace, is a multi-purpose arena/facility located in Mitchell, South Dakota, United States. The Moorish Revival building is decorated with crop art; the mu ...
in Mitchell, South Dakota, which uses cobs and ears of colored maize to implement a mural design that is recycled annually. Another well-known example is the '' Field of Corn'' sculpture in
Dublin, Ohio
Dublin is a city in Franklin, Delaware and Union counties in the U.S. state of Ohio. The population was 49,328 in the 2020 census with a census estimate of 49,037 in 2019. Dublin is a suburb of Columbus. The city of Dublin hosts the yearly ...
Crop circle
A crop circle, crop formation, or corn circle is a pattern created by flattening a crop, usually a cereal. The term was first coined in the early 1980s by Colin Andrews. Crop circles have been described as all falling "within the range of the ...
List of maize dishes
This is a list of maize dishes, in which maize (corn) is used as a primary ingredient. Additionally, some foods and beverages that are prepared with maize are listed.
Ingredients
Corn can be processed into an intermediate form to be cooked furt ...
Post-harvest losses (grains)
Grains may be lost in the pre-harvest, harvest, and post-harvest stages. Pre-harvest losses occur before the process of harvesting begins, and may be due to insects, weeds, and rusts. Harvest losses occur between the beginning and completion of ...
Zein
Zein is a class of prolamine protein found in maize (corn). It is usually manufactured as a powder from corn gluten meal. Zein is one of the best understood plant proteins.Momany, Frank A.; Sessa, David J.; Lawton, John C.; Selling, Gordon W.; H ...
References
Further reading
*
* Byerlee, Derek. "The globalization of hybrid maize, 1921–70." ''Journal of Global History'' 15.1 (2020): 101–122.
* Clampitt, Cynthia. ''Maize: How Corn Shaped the U.S. Heartland'' (2015)
*
*